Bukkit

"Claymores" adds a new sort of weapon to Minecraft. Place a block and it will transform into a customizable disguised Claymore.

Sharing will allow you to feed or heal a player using commands alone or in conjunction with items.

Slimes are boring, and too easy to kill. Sticky Slimes lets slimes harness their sticky properties to slow you down.

SquidBreed implements a mating system for squid, and by doing this, opens up several new doors for players.