I've been playing Minecraft for some time now and probably the most enjoyable experience I've had has been playing multiplayer, not on a big server, but locally with friends. The LAN functionality of mc is already great but there are some features (many of which are already in the Xbox 360 version) that could improve the game even further if implemented in LAN games and small private servers.
More and simpler commands and gamerules
The /gamerule command is great for creating multiplayer games (eg: capture the flag, pvp arenas etc.) but it is kind of difficult to get the hang of. While I was setting up a game with friends they had to wait while I waded through pages of minecraftwiki to find the correct way of inputing the command. What I propose is an ingame menu accessible to the host of the game in which you can toggle things like mob spawning, pvp, whether player names are shown, whether players appear in the map. Something similar to the function already available in the 360 version would be very useful in multiplayer.
The ability to turn autosave off
If you are playing a game which involves tnt, creepers or general destruction, chances are you don't want to keep your world as it is at the end of your game and would much prefer to be able to revert the world to it's original state. Yes you can already do this by going into your program files and finding your save file and duplicating it before you start but this can be complicated as well as leading to hard drive clutter and possibly accidental deletion. It would be much simpler to just turn minecraft's autosave function off and just restart the game in order to reset your world to it's undestroyed state. Again, you can already do this in the 360 version and I could see many situations in which it would be good on PC.
The option to limit world sizes
One of minecraft's key features is it's nearly infinite worlds. Though in most cases it improves the game, sometimes this unlimitedness can be surprising limiting. For example if I were to tell a group of players "I've hidden an item somewhere in this world, your goal is to find it and bring it back to me" it would be impossible, however if when starting said world I had the option to limit it's size (to 1024 by 1024 blocks for example), an impossible task would suddenly be a fun game. This could also for pvp maps, you wouldn't have to waste time defining the boundaries of the arena, instead you could just throw some players into a world and say "last man standing is the winner" and create a simple and fun multiplayer experience. This could also serve to reduce lag and increase challenge in survival mode.
Improved maps
Another great feature of xbox 360 multiplayer is the fact that on maps, each player is displayed as a different colour. This I'm sure, would be very useful when playing small games of SMP. Even using different colours to differentiate between you and other players would be a useful feature if giving each player a different colour was too much trouble (as is understandable in larger games). Another useful feature would be a master map (similar to map 0 before the map update). This map would be pre explored, center on the spawn point and display all players on it and would only be available in creative mode or via the /give command.
More and simpler commands and gamerules
The /gamerule command is great for creating multiplayer games (eg: capture the flag, pvp arenas etc.) but it is kind of difficult to get the hang of. While I was setting up a game with friends they had to wait while I waded through pages of minecraftwiki to find the correct way of inputing the command. What I propose is an ingame menu accessible to the host of the game in which you can toggle things like mob spawning, pvp, whether player names are shown, whether players appear in the map. Something similar to the function already available in the 360 version would be very useful in multiplayer.
The ability to turn autosave off
If you are playing a game which involves tnt, creepers or general destruction, chances are you don't want to keep your world as it is at the end of your game and would much prefer to be able to revert the world to it's original state. Yes you can already do this by going into your program files and finding your save file and duplicating it before you start but this can be complicated as well as leading to hard drive clutter and possibly accidental deletion. It would be much simpler to just turn minecraft's autosave function off and just restart the game in order to reset your world to it's undestroyed state. Again, you can already do this in the 360 version and I could see many situations in which it would be good on PC.
The option to limit world sizes
One of minecraft's key features is it's nearly infinite worlds. Though in most cases it improves the game, sometimes this unlimitedness can be surprising limiting. For example if I were to tell a group of players "I've hidden an item somewhere in this world, your goal is to find it and bring it back to me" it would be impossible, however if when starting said world I had the option to limit it's size (to 1024 by 1024 blocks for example), an impossible task would suddenly be a fun game. This could also for pvp maps, you wouldn't have to waste time defining the boundaries of the arena, instead you could just throw some players into a world and say "last man standing is the winner" and create a simple and fun multiplayer experience. This could also serve to reduce lag and increase challenge in survival mode.
Improved maps
Another great feature of xbox 360 multiplayer is the fact that on maps, each player is displayed as a different colour. This I'm sure, would be very useful when playing small games of SMP. Even using different colours to differentiate between you and other players would be a useful feature if giving each player a different colour was too much trouble (as is understandable in larger games). Another useful feature would be a master map (similar to map 0 before the map update). This map would be pre explored, center on the spawn point and display all players on it and would only be available in creative mode or via the /give command.
This would just give players the option to turn off autosave if they wanted, it wouldn't get rid of it completely.