WowAce

ChatAssist2

Displays the zone level ranage of the zone you are in and also gives you a suggest zone and instances to be in.

Adds options to create customized layouts from within grid.

Database of FlightMaster locations for HandyNotes

TradeBar

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

Shared handling of media data (fonts, sounds, textures, ...) between addons.

Library to help with querying unit talents.

ScoreSort

PetBar

Stable

Allows frames to be dragged around, without permanently changing their position.

Ironi's Encounter Event Tracker

FuBar_NetStatsFu

PricePer

Swiss Army knife for instances, including player tracking, ignore buttons, loot tracking, notes, and more.

Privacy2

Modifies the inbox into a scrollable inbox, including open all options

Meeuuuh

Used to visualize and change values of variables/variable-trees in game