Arguably the best Minecraft Custom Map ever made:
http://thevoxelbox.com/minecraft/maps/
Oh yeah and Update that I competely missed
11w49a[2] December 8, 2011
Sheep eat grass and regain their wool.
When sheared, sheep drop 1-3 wool instead of 2-4.[3]
Added multiple languages.
Added a "spawn mob" egg item to creative mode.
Debug features:
Pressing B changes gamemode.
Bug fixes:
Farmland is no longer destroyed by items and particles.
Corrected a setTileEntity multiplayer bug.
Corrected a powered rail bug.
Corrected a redstone update bug.