WowAce

Switch macro depending on zones or BigWigs boss modules.

Add-on that allows you to setup and quickly switch between different profiles of your action bars

PT3Browser

Mutt (Macro Update Target Tool) provides slash-commands that can patch the predefined targets in your macros.

Highly-configurable shield / absorb tracker.

BA3_SpellAbilities

Antagonist

MorgDKP

CandyBar style cooldown display

Show what quests have changed

Adds your name to chat messages

Shows skills in a tooltip and allows them to be used.

Keeps track of your current location.

Tracks, transmits and displays the cooldowns of your raid.

Adds unreal tournament style sounds to PvP encounters.

Displays Instance Maps

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

Shows class colors on player nameplates and names

Keeps track of current money and all your characters on one realm.

Litmus