WowAce

Displays Instance Maps

Provides one or many informational windows with optional interactive widgets.

Tooltip of awesomeness. Moo. It'll graze your pasture.

Display aura information inside action buttons

Alternate Power- and Combopoint/SoulShard/HolyPower-bar

Redirect character errors, system messages and information messages.

Antagonist

Sells all junk in your inventory at once.

Configurable Castbars

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

Remember locations that city guards direct you to for HandyNotes

Adds a status to Grid for debuffs applied by Raid Bosses.

mount and companion manager

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

Prat

tracks and share quests between your party

Smooth combat HUD based on ArcHUD2

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

Automated smart raid marking to speed up trash clearing in instance runs

A simple combat log that displays events similar to SCT