WowAce

Configurable Castbars

Manufac

Keeps track of HoTs, DoTs, Buffs and Cooldowns. With audio and text alerts to refresh them.

OneBag is a replacement for the default game bags that combines all the bags into one frame.

Watches your chat, flagging missplled words, and offering correctly spelled suggestions.

Displays the remaing cooldown of the action you tried to use

XRS

Quest History tracker and shows lists of quests in each category

Redirect character errors, system messages and information messages.

CandyBar style cooldown display

A library to help with localization of factions.

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

GotWood

Auto repair + shows durability.

Regain that wasted space!

Switch macro depending on zones or BigWigs boss modules.

PT3Browser

Automated smart raid marking to speed up trash clearing in instance runs

Try on different gear and see their total stats and their differences. In short, an ingame CT-Profiles-like addon.

Inspects all members of raid and saves in database, as well as lists people's dkp values