WowAce

KillingSpree

RangeRecolor

FuBar_HonorFu

ChatHighlighter

Displays Pet Info for Hunters and Warlocks. Also keeps track of Stables and Pet and Demon skills.

Shows skills in a tooltip and allow them to be used. Also keeps track of Cooldowns.

Fires events whenever a raid member "fails".

item2phpBB

Adds manabars to the sides of Grid frames.

Collects, analyzes and presents information about the virtual economy.

lern2count adds ABinfo castcounts to spell and actions. It has a builtin reagentcount too.

Improved Quest Tracker

Track of your tradeskills across characters, create small buttons for them and track cooldowns.

An Atlas Plugin that displays arena maps.

StitchUI

Tracks profession specific cooldowns and items across all your characters

FuBar_CheckStoneFu

Gives detailed descriptions of particular localities, as zones or instances, and provides optional TomTom integration.

Note + rep tracking for players, with guild data sharing.

Utility library with shared functions and data for various addons by NeoTron.