Bukkit

Mentioner is a plugin to notify the players when they are mentioned in chat with a sound.

A brotastic nickname manager

Splits the chat into channels. You can switch between the channels just by clicking.

RCON allows access to console from in-game.

A powerful permissions system addon for Essentials/PEX/etc

Hit a sign, run a hidden command!

Adds some usefull command like /heal, /fly, /vanish, /invsee and much more

A light-weight, easily/highly configurable, Chat Channel plugin.

LovelyStaffList currently lists all of the online staff members on the server using the commands /who or /online.

ReporterPL

EchoTell

Troll

AntiBadWord

ConvoSync allows players on separate Minecraft servers to chat with each other.

AntiCommandKill

Standalone Chatplugin with Timestame, Replacer, Autokick, Autoban

A simple countdown to start events

A simple shout plugin that lets your users do /shout <message>

Allows message broadcasting with /broadcast. Configurable prefix

Players can choose there own titles. Includes nametags (above heads).