WowAce

Queing of /who and SendWho() queries and a much better interface (see docs), with gurantee to be executed & callback.

Grabs bugs for the bug sack.

A library to provide information about zones and instances.

Provides one or many frames for dumping text into.

Provides one or many informational windows with optional interactive widgets.

AddOn development framework

an embeddable library providing an abstraction layer for tracking and querying Blizzard's Nameplate frames with ease and effi...

Additional information about player spells.

Library that tracks incoming heals

Libra

A powerful, comprehensive utilty for displaying graphics and information based on buffs, debuffs, and other triggers.

LibItemInfo-1.0

Records Damage and Healing for Graph Based Display.

Simple and Advanced combined - Bartender4 ActionBar AddOn

Library to check whether an item is equipable / appropriate for a given class

Collects Herbs, Mines, Gas Clouds, Archaeology, Treasure and Fishing locations and adds them to the worldmap and minimap

Handy notes for your maps

A framework for chat ehancement modules.

A library to handle rearrangement of blizzard's frames when bars are added to the sides of the screen.

"Debug" code free since '93!