Bukkit

Set up custom villager shopkeepers

Snowball-hit-detection-game-plugin!

Rentable Advertising Signs

Displays text on signs individual differently for each player looking at it.

Inexpensively protects your ores from cheaters.

HomeStations offers home<->spawn teleportation via stations instead of commands

Dreamworld gives players the chance to wake up in an other, specified "dream" world.