WowAce

Scan for rare mobs so you can find them and their loot

Library providing multi-column tooltips.

A fancy LDB reputation display, show faction reputation and reputation change history

Show the appearance of an item when you mouse over it

Set and manage character notes that are displayed in unit tooltips and /who results.

Complete tradeskill information.

Manages social information with a focus on main-alt associations.

Item stat breakdown, analysis and comparison

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

Collectinator is an addon which will scan your pets and mounts and provide information on how to obtain them.

Lightweight but powerful auction house interface

Displays item durability and repair cost.

"Your quest log is full". How many quests do you have in your log?

Kaliban's Class Loot List Star Display

StarTip (Tooltips from Outerspace)

Simple and super light-weight tracking of profession links for all your alts.

Interacts with TinyTip modules, either integrated or standalone, to provide extra centralized functionality. Required for an ...

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

Adds various information based on PeriodicTable to item tooltips.

Add-on that shows in a unit tooltip window a number of killed mobs of the same kind