WowAce

Keeps track of HoTs, DoTs, Buffs and Cooldowns. With audio and text alerts to refresh them.

Disease Tracker for Death Knights.

Adds a button to your character and inspect window that shows a summary of gear enchants and gems.

MountUp

YssGuildShop

Friends & Guild Data Broker plugin.

Gathers statistics on certain chance-on-use spells, also known as procs.

A library for PvP and Battlegrounds

Provide plenty of links

NBuffBars

Generates and posts random Chuck Norris facts to a specified chat medium.

Omnibus

WhoDrop

Improved Quest Tracker

Helps you automate selling stuff.

A collection of useful (guild management) tools and utilities for smarter than average bears.

Adds on-screen buttons for the farming tools and seeds.

Tracking and ranking of dps/hps in a guild.

ItemSync the happy item gatherer and toolkit.

Heads Up Display with Player and Target Info