WowAce

Allows you to preview weapon glow in Dressing Room.

Allows the user to preview and track their progress in the collection of various transmogrification appearance sets

GrindStatus

Does stuff for sachmo

A replacement tradeskill window for Classic

Keeps track of your current location.

Shows ZoneInfo on the World Map in a perfectly cromulent fashion.

Death analysis tool

Switch macro depending on zones or BigWigs boss modules.

Angry Raid Points

Compact & customizable filtering, monitoring and grouping of buffs and debuffs

View bank, inventory, mail, equipped and guild bank contents from any character anywhere!

Tracks SendAddonMessage Spam

MiniPet, Always keep your little companion with you, based on the work of Carra.

Track all threat redirection ability transfers and cooldowns (Misdirection and Tricks of the Trade).

Compact rune and proc display for Death Knights.

Target Debuff monitor. Stacking aware, giving current and potential debuff status.

A library to provide a clean dropdown menu interface.

Fires events whenever a raid member "fails."

An auction house AddOn to make the life of each fence easier.