WowAce

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

Quest History tracker and shows lists of quests in each category

Tracks the HoTs you cast.

Bulk mail sending made really easy

One large inventory.

Adds World Quests to the quest list

A blizzard group finder replacement

Raid Frames using the oUF framework.

Antagonist

Marks the locations of Midsummer Fire Festival bonfires on the worldmap and minimap.

Provides one or many informational windows with optional interactive widgets.

Provides access to all Portal and Teleport spells on right click of one button.

Create panels for customizing your UI, sucessor to eePanels

Library providing mappings between trade skill recipes, spells and created items

Bayi's Extended Questlog

mount and companion manager

XRS

Adirelle's unit frames, based on haste's oUF.

A Friend-Enemy-Unit-Frame for battlegrounds.

Cleans up minimap buttons and makes them accessible through a pop out menu!