WowAce

Mage Portal Whisper: whisper custom message when someone asked for a portal but youre busy.

Monitors the combatlog identifying players from the oposite faction near you.

Tells your party members when you interrupt stuff, or fail to do so.

Uses linear regression and a log of hitpoint values to estimate how long a boss has left to die and reach execute range.

TwiCo

Show a bar indicating the remaining lifetime of your temporary pet

Object-orientation library

With Mists of Pandaria Blizzard publish all characters from an account unless you disable that 'feature'. This addon warns you.

Show a bar indicating the unit's Burning Embers count.

obRaidAssist

Shows attachment count in Inbox icon.

Synchronise friends among your characters

Experimental timer library that uses the Animation system as a scheduler.

EyeCandy

Relays item drops to your guild chat.

A customizable buff/debuff display replacement for the default Blizzard frames (with right click cancelaura support).

How much of your life have you spent ingame?

MeleeBuffs

BetterMagnet

New screenshot keybinds to automatically hide the interface during the shot.