WowAce

Provides data about all artifacts in the player's possession.

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

AddOn development framework

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

Adds an addon manager in game via the 'Addons' menu. Special support for multi-part addons. Based on rMCP by Rophy.

A library to help with localization of talent trees.

Bag and item management utilities

Library providing mouse-click support for LibQTip-1.0.

Simple embeddable publish-subscribe implementation.

A library to provide information about zones and instances.

Dropin replacement library for SetBackDrop

A library to help with localization of item types and subtypes.

Library to handle and store information about frame that are possible targets to anchor other frames to.

LibGUIFactory-1.0

A library allowing for easy creation of graphs

A library to help with localization of Zones.

A library to help with localization of in-game item sets.

A library to provide a clean dropdown menu interface.

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

TabletLib