I've gotten all up into configuring and running Minecraft servers between co-administrating the Outpost with Robotnikman and running my own server on my VPS. Craftbukkit, hands down, could either be the best mod or tie for best alongside Forge.
One thing you might mistake, though, is that Craftbukkit is something you only run on a remote host and have other people besides yourself play on, but having to often quality assure the plugins and permissions I configure, running a local Craftbukkit instance is an invaluable way to learn what works and what doesn't before making it available to other players. BUT, I've stopped and considered more than once, could a local Craftbukkit also be an invaluable way to play?
Well, that was a stupid question since odds are any modern server you play on runs Craftbukkit to pick up the slack vanilla leaves in its player permissions and protections. So yes--it's an invaluable way to play. Especially when you stop to consider new ways of playing the game it can bring to singleplayer.
Forge is often touted as the numero uno mod(loader) for Minecraft and I'll admit that in terms of adding new content, it's unparalleled. Bukkit works in a way that's so completely different comparing what the two of them do is apples and oranges, whereas Forge adds new content to the game, Bukkit attempts to stretch and expand the gameplay. Respectfully, both I think keep the game fresh and I don't think either does a better job than the other without being weaker in different areas. Craftbukkit, for example, cannot add any sort of new block or item to the game as far as editing the tags and block data of existing items. Forge, however, lacks a lot of command based mods that most Craftbukkit plugins are based on (such as our beloved Essentials plugin).
One mistake you cannot make, however, is thinking that when seeing a cool mod it can load up easily into Craftbukkit. I generally have two rules of finding compatability in plugins which is if it 1) adds new blocks, items and mobs to Minecraft and 2) isn't found on http://dev.bukkit.org/bukkit-plugins/ then it will not work. Usually because those mods are Forge based. I've heard requests more than once for mods to be implemented onto the Outpost which can never run because they're for Forge and not Craftbukkit.
That being said, let's see what Craftbukkit can do to make singleplayer a little more interesting without having to use any client mods. I recommend at the very least you have 4gb of RAM which will be more than enough to run the server and your client at the same time.
Installing Craftbukkit
Firstly, I'm assuming that you run Windows. If not, I'm sorry that you have to game on a non-Windows PC (jk jk). It's really quite simple. First, make a new folder on your desktop named Bukkit (or name it anything--it doesn't really matter). You'll then need two things which is the server jar file and a launch script so you don't have to manually start it from the command line every time you run it. Here's a relatively easy launch script--
Use a simple text editor like notepad to create this file, and save it in the Bukkit folder as start.bat. If you're a little lean on memory then you can change -Xmx1024M to -Xmx512M. This signifigantly reduces the amount of memory the server will use, however this means fewer plugins will be able to run simultaneously. If you've got the memory to spare and want to use a bunch of plugins simultaneously you can specify it as maybe 1536M (1.5gb) or 2048 (2gb). Just remember to leave enough for your client to play as well. There's a few more verbose arguments you can use such as setting permgen memory size, startup memory, but this simple one above get's the job done without being too technical.
Speaking of Notepad, if you're going to configure server files you're going to need something with a bit more power than Notepad. Notepad++ will better configure .yml files which is predominantly the format you'll find most bukkit plugin conf files in.
Also, after you download the server jar you'll want to name it simply to craftbukkit.jar which will reflect the jar file specified in the script.... or change the script to specify the jar you're using. I prefer doing the former.
Running the Server
After you have created the start script, you should be able to launch the server by running this script. Craftbukkit will generate the default folders and files it needs to run and you can monitor the server from the command console that the script opened. You can use that to perform basic Minecraft commands such as /op [yourself], /ban [jerk] or /stop which will gracefully stop the server (never just close the console or you might lose world save progress. Always /stop). If you op yourself, you can perform all these commands ingame. It's essentially the same as having cheats enabled on LAN.
From your Minecraft client, you can now connect to this server by selecting Multiplayer, Add Server and then setting localhost or 127.0.0.1 as the server address.
By default, it's gonna feel a lot like vanilla survival.... because for the most part, it is. I have a few fun suggestions, however, to spice up SSP. These will all generally come in .jar files which you place in the plugins folder of your server's folder. After craftbukkit loads the mods during startup, it will generate their respective folders and configuration files in the plugins folder. I recommend, however, /op'ping yourself and playing that way so you don't have to dive too far into things such as having to get a permissions plugin and setting it up for just yourself to play on.
ExtraHardMode
I gave this a spin on the Wooden Axe's Origin server. I like to call it Asshole Minecraft, myself. For the full effect, I recommend playing it without Essentials. Y'see, this adds a lot of challenge to survival gameplay. If you don't have a bed spawn set, you are re-spawned thousands of blocks away from where you die, having to start entirely from scratch. Dirt and cobblestone are also prone to gravity in EHM. No more dirt or cobble bridges across wide gaps like lava in the nether or a bridge across the ocean. It's also not uncommon in EHM for dirt to have cave-ins from underneath and likely suffocate you to death.
Rain snuffs out torches, you can't place torches down at diamond layer (fucking hate this), your pickaxes have signifigantly less durability so stripmining is pointless. Zombie Pigmen are always hostile in the Nether. I could go on and on, but if you're a huge fan of survival and hard difficulty or Hardcore don't do it for you, this is what you want. Prove your mettle and do a combination of Adventure mode (/gamemode 2) and Hardcore while playing this, and you are a Minecraft God. Hardcore can be enabled on the server by going to the bukkit folder, opening the server properties file and setting Hardcore to TRUE (for which you have to delete or rename the current world folder and let craftbukkit generate a new one).
Dynmap
Dynmap is a map of your server's world viewable from your browser! Personally, I don't see as much use for Dynmap as I do for Zan's Minimap with well appointed waypoints. But the advantage Dynmap has over a minimap is that the whole world is viewable which, if you're like me, make it easy to find builds you lose and can never find again. It's very satisfying, I've found, to take an exising world in your .minecraft folder and use it on the server and be able to see the whole of the world you've discovered from an overhead view. I've found some builds I lost ages ago because I built them too far away from the spawnpoint with Dynmap.
WorldBorder
WorldBorder can set limits on how far you can travel out in your world. Initially, this might not seem useful or beneficial to SSP, but take into consideration the /fill and /trim commands worldborder adds to the game. If you set the borders of your world to maybe 3000 block in all directions, you can use /fill to begin generating all the undiscovered chunks you haven't explored (combine that with dynmap and you have an all encomapassing worldmap). Or if your world is getting a bit too big and you'd like to save some precious hard disk space, /trim will being removing unloaded chunks outside the worlds border (hope you don't have anything out that far you wouldn't mind losing!).
A note about /fill, though, is that it's going to suck up quite a bit of hard disk space to fill in all the chunks. Unless you have hundreds of gigabytes you aren't using, /fill isn't that great an idea.
Essentials
The use for this in SSP should almost be self-explanatory when you take into consideration home setting and warps.
Craftbook
Craftbook brings a lot of fun, automation features to Minecraft. Such as creating toggleable gates, light switches, bridges and new uses for redstone with IC's. I've personally found gobs of ways to use IC's to automate tasks such as endlessly breaking and collecting cobblestone from lava/water cobble generators. There's also the cultivator which automatically tills land around it and a planter which fills the tilled land with seeds. It really mititgates the tediousness often collecting materials can create while giving you more time to focus on building.
Worldedit
This is a bit of a stretch. Yeah, it's honestly a creative tool, not survival. But there's really two unwieldy things about Worldedit client installs vs using it on a bukkit server in that with SinglePlayerCommands I'm personally not keen on modifying the Minecraft jar file with individual mods opposed to being loaded through Forge or Craftbukkit. SinglePlayerCommands/Worldedit, however, does not yet have a Forge version. It works wonderfully on Craftbukkit, though, and from my own personal experience SPC client installs were often buggy and inaccurate.
You can go to http://dev.bukkit.org/bukkit-plugins/ to find more plugins which can enhance singleplayer Minecraft. Sure, sure--you could just play on a server, yeah. But sometimes if you're like me you just like to get away from the chat boxes and PVP.... or maybe your internet's down and vanilla singleplayer doesn't do it for you anymore.
One thing you might mistake, though, is that Craftbukkit is something you only run on a remote host and have other people besides yourself play on, but having to often quality assure the plugins and permissions I configure, running a local Craftbukkit instance is an invaluable way to learn what works and what doesn't before making it available to other players. BUT, I've stopped and considered more than once, could a local Craftbukkit also be an invaluable way to play?
Well, that was a stupid question since odds are any modern server you play on runs Craftbukkit to pick up the slack vanilla leaves in its player permissions and protections. So yes--it's an invaluable way to play. Especially when you stop to consider new ways of playing the game it can bring to singleplayer.
Forge is often touted as the numero uno mod(loader) for Minecraft and I'll admit that in terms of adding new content, it's unparalleled. Bukkit works in a way that's so completely different comparing what the two of them do is apples and oranges, whereas Forge adds new content to the game, Bukkit attempts to stretch and expand the gameplay. Respectfully, both I think keep the game fresh and I don't think either does a better job than the other without being weaker in different areas. Craftbukkit, for example, cannot add any sort of new block or item to the game as far as editing the tags and block data of existing items. Forge, however, lacks a lot of command based mods that most Craftbukkit plugins are based on (such as our beloved Essentials plugin).
One mistake you cannot make, however, is thinking that when seeing a cool mod it can load up easily into Craftbukkit. I generally have two rules of finding compatability in plugins which is if it 1) adds new blocks, items and mobs to Minecraft and 2) isn't found on http://dev.bukkit.org/bukkit-plugins/ then it will not work. Usually because those mods are Forge based. I've heard requests more than once for mods to be implemented onto the Outpost which can never run because they're for Forge and not Craftbukkit.
That being said, let's see what Craftbukkit can do to make singleplayer a little more interesting without having to use any client mods. I recommend at the very least you have 4gb of RAM which will be more than enough to run the server and your client at the same time.
Installing Craftbukkit
Firstly, I'm assuming that you run Windows. If not, I'm sorry that you have to game on a non-Windows PC (jk jk). It's really quite simple. First, make a new folder on your desktop named Bukkit (or name it anything--it doesn't really matter). You'll then need two things which is the server jar file and a launch script so you don't have to manually start it from the command line every time you run it. Here's a relatively easy launch script--
java -Xmx1024M -jar craftbukkit.jar -o true PAUSE
Spoiler
Use a simple text editor like notepad to create this file, and save it in the Bukkit folder as start.bat. If you're a little lean on memory then you can change -Xmx1024M to -Xmx512M. This signifigantly reduces the amount of memory the server will use, however this means fewer plugins will be able to run simultaneously. If you've got the memory to spare and want to use a bunch of plugins simultaneously you can specify it as maybe 1536M (1.5gb) or 2048 (2gb). Just remember to leave enough for your client to play as well. There's a few more verbose arguments you can use such as setting permgen memory size, startup memory, but this simple one above get's the job done without being too technical.
Spoiler
Speaking of Notepad, if you're going to configure server files you're going to need something with a bit more power than Notepad. Notepad++ will better configure .yml files which is predominantly the format you'll find most bukkit plugin conf files in.
Also, after you download the server jar you'll want to name it simply to craftbukkit.jar which will reflect the jar file specified in the script.... or change the script to specify the jar you're using. I prefer doing the former.
Running the Server
After you have created the start script, you should be able to launch the server by running this script. Craftbukkit will generate the default folders and files it needs to run and you can monitor the server from the command console that the script opened. You can use that to perform basic Minecraft commands such as /op [yourself], /ban [jerk] or /stop which will gracefully stop the server (never just close the console or you might lose world save progress. Always /stop). If you op yourself, you can perform all these commands ingame. It's essentially the same as having cheats enabled on LAN.
From your Minecraft client, you can now connect to this server by selecting Multiplayer, Add Server and then setting localhost or 127.0.0.1 as the server address.
By default, it's gonna feel a lot like vanilla survival.... because for the most part, it is. I have a few fun suggestions, however, to spice up SSP. These will all generally come in .jar files which you place in the plugins folder of your server's folder. After craftbukkit loads the mods during startup, it will generate their respective folders and configuration files in the plugins folder. I recommend, however, /op'ping yourself and playing that way so you don't have to dive too far into things such as having to get a permissions plugin and setting it up for just yourself to play on.
ExtraHardMode
I gave this a spin on the Wooden Axe's Origin server. I like to call it Asshole Minecraft, myself. For the full effect, I recommend playing it without Essentials. Y'see, this adds a lot of challenge to survival gameplay. If you don't have a bed spawn set, you are re-spawned thousands of blocks away from where you die, having to start entirely from scratch. Dirt and cobblestone are also prone to gravity in EHM. No more dirt or cobble bridges across wide gaps like lava in the nether or a bridge across the ocean. It's also not uncommon in EHM for dirt to have cave-ins from underneath and likely suffocate you to death.
Rain snuffs out torches, you can't place torches down at diamond layer (fucking hate this), your pickaxes have signifigantly less durability so stripmining is pointless. Zombie Pigmen are always hostile in the Nether. I could go on and on, but if you're a huge fan of survival and hard difficulty or Hardcore don't do it for you, this is what you want. Prove your mettle and do a combination of Adventure mode (/gamemode 2) and Hardcore while playing this, and you are a Minecraft God. Hardcore can be enabled on the server by going to the bukkit folder, opening the server properties file and setting Hardcore to TRUE (for which you have to delete or rename the current world folder and let craftbukkit generate a new one).
Dynmap
Dynmap is a map of your server's world viewable from your browser! Personally, I don't see as much use for Dynmap as I do for Zan's Minimap with well appointed waypoints. But the advantage Dynmap has over a minimap is that the whole world is viewable which, if you're like me, make it easy to find builds you lose and can never find again. It's very satisfying, I've found, to take an exising world in your .minecraft folder and use it on the server and be able to see the whole of the world you've discovered from an overhead view. I've found some builds I lost ages ago because I built them too far away from the spawnpoint with Dynmap.
WorldBorder
WorldBorder can set limits on how far you can travel out in your world. Initially, this might not seem useful or beneficial to SSP, but take into consideration the /fill and /trim commands worldborder adds to the game. If you set the borders of your world to maybe 3000 block in all directions, you can use /fill to begin generating all the undiscovered chunks you haven't explored (combine that with dynmap and you have an all encomapassing worldmap). Or if your world is getting a bit too big and you'd like to save some precious hard disk space, /trim will being removing unloaded chunks outside the worlds border (hope you don't have anything out that far you wouldn't mind losing!).
A note about /fill, though, is that it's going to suck up quite a bit of hard disk space to fill in all the chunks. Unless you have hundreds of gigabytes you aren't using, /fill isn't that great an idea.
Essentials
The use for this in SSP should almost be self-explanatory when you take into consideration home setting and warps.
Craftbook
Craftbook brings a lot of fun, automation features to Minecraft. Such as creating toggleable gates, light switches, bridges and new uses for redstone with IC's. I've personally found gobs of ways to use IC's to automate tasks such as endlessly breaking and collecting cobblestone from lava/water cobble generators. There's also the cultivator which automatically tills land around it and a planter which fills the tilled land with seeds. It really mititgates the tediousness often collecting materials can create while giving you more time to focus on building.
Worldedit
This is a bit of a stretch. Yeah, it's honestly a creative tool, not survival. But there's really two unwieldy things about Worldedit client installs vs using it on a bukkit server in that with SinglePlayerCommands I'm personally not keen on modifying the Minecraft jar file with individual mods opposed to being loaded through Forge or Craftbukkit. SinglePlayerCommands/Worldedit, however, does not yet have a Forge version. It works wonderfully on Craftbukkit, though, and from my own personal experience SPC client installs were often buggy and inaccurate.
You can go to http://dev.bukkit.org/bukkit-plugins/ to find more plugins which can enhance singleplayer Minecraft. Sure, sure--you could just play on a server, yeah. But sometimes if you're like me you just like to get away from the chat boxes and PVP.... or maybe your internet's down and vanilla singleplayer doesn't do it for you anymore.