WowAce

Static library of wow map data

Reports in raid chat whenever a raid member "fails." /EnsidiaFails to configure.

Loudmouth

Highly-configurable shield / absorb tracker.

Adds Archaeology items to AdiBags virtual groups

View an image of your guild vault from anywhere.

Mutes various chat related annoyances while in capital cities and instances.

QuestAnnouncer

PT3Browser

Sniff

Provides a quick display for the LFG Call to Arms

IncomingHealsLib

Keeps track of time played and rested XP across your characters.

Database of FlightMaster locations for HandyNotes

Adds your damage to Scrolling Combat Text

Shows where the equipment of inspected users or yourself is from.

Tracks skill and tradeskill costs and progressions, as well as trainer locations.

FuBar_TrainerFu

Add-on that shows in a unit tooltip window a number of killed mobs of the same kind

Keeps track of your top hits, heals, criticals, etc.