WowAce

Configurable Castbars

Checks Raid Buffs/Flasks/Consumables. Tunable alerts for misdirects, taunts, cc breakage, rez, dispel and interrupt

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

Manufac

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

Prat

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

Displays the remaing cooldown of the action you tried to use

Redirect character errors, system messages and information messages.

XRS

Quest History tracker and shows lists of quests in each category

Auto repair + shows durability.

Database of Diminishing return categories and general data

CandyBar style cooldown display

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

GotWood

Regain that wasted space!

Switch macro depending on zones or BigWigs boss modules.

A library to provide a markup syntax

PT3Browser