WowAce

Right-click on minimap blips to open a targeting menu (out of combat).

A loot distribution addon meant to improve master looting during raids.

Add item levels to Inventorian

Provides the the health and target of by an unit targeted mob (meant to be used for tanks).

Shows a frame to track your debuff on Malygos in phase three.

Light-weight enhanced casting bars

Adds indicators to the sides of Grid frames.

For Developers (of Addons which uses LibWho-2.0): show queues and queries in realtime

GCInfo

Shows a money overview for your current realm in the tooltip on the money in your bags

Show an in combat indicator

LD50_abar

Omniscience

Good looking, smoothy and helpful nameplates

LFD status via a DataBroker display rather than the minimap.

ArenaHistory

Replacement for WoW's flash/fade functions.

Tracks specialization and talent data for group members

SurgeonGeneral Listen CLient

This addon helps with daily quests.