This is so basic and very useful on a multiplayer server
-You could lock your chests to not get things stolen from under your nose
-along with the ability to make chain and secure things, namely chests
-locks for wooden doors
-Locks for iron doors, as opposed to cumbersome plates
and as a side note why mot the ability to craft gates? It seems anticlimactic to have an awesome castle with a two block tall door.
I'm not really sure on what you are suggesting here, the locks on chests makes sense and have been suggested before (I even think there is a mod for it).
A lock for doors isn't really much point as one can just break the wall.
However I do see potential in a key and lock system for custom made adventure maps. That way you can hide keys that fits specific locks instead of the current way of having redstone torches, buttons, levers or pressure plates that needs to be placed in specific locations to open doors.
Most servers I've seen already offer a chest protection system, that deals with signs. The same goes with doors/ houses, if its protected in a multi-player server you shouldn't be worried about someone just walking in or breaking into the house. As far a as your request for (what I'm assuming are) large (animated) gates, Bukkit should have that covered in the near future now that they are working along side Mojang.
-You could lock your chests to not get things stolen from under your nose
-along with the ability to make chain and secure things, namely chests
-locks for wooden doors
-Locks for iron doors, as opposed to cumbersome plates
and as a side note why mot the ability to craft gates? It seems anticlimactic to have an awesome castle with a two block tall door.
A lock for doors isn't really much point as one can just break the wall.
However I do see potential in a key and lock system for custom made adventure maps. That way you can hide keys that fits specific locks instead of the current way of having redstone torches, buttons, levers or pressure plates that needs to be placed in specific locations to open doors.