WowAce

A library to help with localization of in-game subzone names.

Show buffs on nameplates.

tracks and share quests between your party

StarTip (Tooltips from Outerspace)

Toggles WoW to the forground on events.

Tells you who bought your auctions.

Shows you the radius of your totems.

GemCensus inspects people and records which gems they have socketed. Then displays which gems are the most popular.