WowAce

Enables cooldown notification between players and allows party members access to each-others spell books.

It's a doodle pad for doodling with doodles.

Adds aura indicators to unit frames

Provides quick notification (sound and visual) of your tanking status of your current target. Meant for tanking.

A shaman mod

Combat log replacement

Mob respawn timers

A simple addon that warns you if your pet isn't attacking while you're in combat.

Display an arrow that points to a raid/party member anchored to raid frames

RBM

Keeps a list of all items you want and shows how much you need.

A seperate focus bar, with focus gain prediction and rotation forecast.

DreamChat

LibDogTag-2.0

SpellWatch

AutoFIR

Tells you which blob to kill at the Yor'sahj encounter in Dragon Soul.

Show who is targeted by at least one enemy, and the casting progress of the incoming spell.

A frame with a text that gives you the amount absorb left on target, or in TankMode absorbs left on yourself.

Omniscience