WowAce

Leveling guides for trade skill professions.

A Data Broker plugin to show AddOn memory usage.

Communicates with guild members for their positions on the world map

Replacement for the default minimap.

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

Shows where the equipment of inspected users or yourself is from.

Dynamically atering layout in raid environment (Tanks, Ranged / Melee DPS, Healers)

FuBar_tTracker

CraftList

EasyTrack

TGuildFrame

Simple Bars for your Shaman's weapon buffs and shield spells.

Damnation

tekProber

FuBar_NavigatorFu

Customize the appearance of the chat bubbles.

Allows frames to be dragged around, without permanently changing their position.

SalvationKiller

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

Handles the assignment, coordination, and announcement of many parts of the Lich King encounter in Icecrown Citadel.