WowAce

Handles the assignment, coordination, and announcement of many parts of the Lich King encounter in Icecrown Citadel.

Does a /who search of multiple dungeons.

Quixote

Automatically invites player from templates.

Replacement for default bags.

Make it easy to explain bosses in Raids.

Makes your item stats shine!

Lets you drag UI frames around

EnchantList

Sets the DND flag, when are in combat.

RaidInfo

Automatically sells low quality gray items and selected white items to the vendor.

NBuffBars

A 'channeling spell'-tracking addon for Affliction Warlocks. Drain Soul, Drain Life/Harvest Life and Malefic Grasp.

Shows who controls Wintergrasp and the time until the next battle.

Warnings about tanking specific abilities

Displays info about who rolled Need/Greed/Pass on items that are currently rolled for

A Data Broker add-on for quickly switching your specialization with gear set and loot specialization.

BigTrouble

Prospecting and Disenchanting Aide