WowAce

Enhances the StackSplitFrame with numbered Buttons, a '1-Click Mode' and a 'Auto Split Mode'.

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

Draws some lovely 3D portraits in the standard Blizzard artwork.

RaidInfo

Expo

Lists Pots and Herbs you got on all chars and allows you to specify color coding

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

Stable

Automatically invites player from templates.

Makes those pesky garrison animations go away.

Relog

Needja Tracker

LibDataBroker plugin showing some random XP related data

StatStain

DarkCandy

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

PartyToGo

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

Does a /who search of multiple dungeons.

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