WowAce

Good looking, smoothy and helpful nameplates

Replacement of build-in loot frame

Tracks Black Market Auction House auctions.

It's a doodle pad for doodling with doodles.

Display who crossed the charges on Thaddius

Display combo points for Arcane Blast debuffs

A FPS Data Broker plugin.

WeaponRebuff

A Data Broker plugin to display how long you've been playing

XP and Reputation bars

Combat log replacement

TrickOrTreat

Keeps track of your reagents.

This is an add-on to block incoming guild/party/duel requests (except for friends/party/guild) (previously ASSBlock)

Omniscience

Reslack

Show who is targeted by at least one enemy, and the casting progress of the incoming spell.

Shows at-a-glance what raid buffs/debuffs you have.

Interface-central mount management

Complain about crowd control breaks.