WowAce

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Aura alarm.

Objective Tracker

Bind spells, items, and macros to keys, without using action buttons

Simple Spell Alert

Show a texture on demand

Monk Brewmaster/WindWalker Priority and Buff/Debuff Tracking Tool

Calculates incoming damage avoidance and mitigation

A library to handle rearrangement of blizzard's frames when bars are added to the sides of the screen.

Test whether the player can really dispell a buff or debuff, given its talents.

Ace2'd version of the "Visor" frame-modifictaion AddOn. All code in this addon is copyrighted 2006 by its authors, which are...

EyeCandy

Fancy up the ExtraActionButton frame

Adds 3 corner indicators to each corner of the Grid frames.

Keeps track of resurrection spells cast in a group

BananaBar2

BiGOpt

AltClick an item in your bag to add it a mail, auction, or trade frame, and alt-click to buy a stack if reagents.

Displays an alert whenever you loot an item for the first time.

LittleTrouble