WowAce

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

Displays the remaing cooldown of the action you tried to use

TomTom CrazyArrow pointing to the targeted group member

Adds mob patrol paths to your map.

Raid Frames using the oUF framework.

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

Babble-2.2

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

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

Bayi's Extended Questlog

Incubator

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

Smooth combat HUD based on ArcHUD2

One large inventory.

Bulk mail sending made really easy

Shows simple Buttons for your Cooldowns :)

Quest History tracker and shows lists of quests in each category

Questing minion

A blizzard group finder replacement

Provides one or many informational windows with optional interactive widgets.