Bukkit

Message Rainbowizer, Color Parser, and reference.

Easily promote or demote users

ExplodingAnimals

Let people buy ranks with signs!

A simple player warping plugin

Fells, or chops down, trees automatically, similar to the Timber mod.

TeamChat2

Tired of Factions? Get Sectors.

TheMaze

OreRate

Good Plugin

Creepersday

Weed Reloaded!

Skills introduces passive and active skills to Minecraft.

AdminPlus is the new way to spy on your players!

mmLottery

CurrencyHandler is a Economy API that features support for more than just money.

A simple plugin which allows you to date/marry players on servers

Not only for controling the chat, yet that useful :P

Castle Defence plugin made for Minecraft