WowAce

Reverse Engineering will drill down and search your tradeskills for their elements

Debuff Monitor: A Powerful & Configurable Raiding Tool

Evaluates your gear

Embeddable chat throttling library with traffic shaping and priorities

Quest helping: fetching items to use, that sort of thing.

Voyeur

ClosetGnome_Fishing

Gives equipped and overall iLvl to indicate the quality of a character's gear.

WeaponRebuff

Makes grid QuickHealth aware

XP and Reputation bars

Shows the price of a single item in the Auction House.

RS_ClassColors

Enhances the Equipment Manager to let you control the helm/cloak visibility for each set.

Transcendence Monitor for Monks

Adds easier gear switching to FuBar.

Enable/Disable addons for your character in game

Shows a frame to track your debuff on Malygos in phase three.

A simple data broker display for current Artifact Power

Allows custom-triggered boss mod timers to be created