WowAce

RBM_Config

FuBar_CRDelayFu

Shows a countdown bar for the duration of auras (e.g. HoTs, DoTs)

Good looking, smoothy and helpful nameplates

Helps to track outgoing mails

Adds tier set number and difficulty indicators to tier item tooltips.

Shows optimal target to use various area healing spells

Shows current/dot cast haste values

Shows a window displaying any raid member below 10,000 health during the Chimaeron encounter.

Target assistance by automatic rewriting of macros

A simple addon that warns you if your pet isn't attacking while you're in combat.

LibBabble-Spell-3.0

"Your quest log is full". How many quests do you have in your log?

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

Lexan

Allows combined aura detection. motw + gotw, all 4 mage int buffs, etc. in one status.

Simple, nice-looking power bar addon for all classes.

Provides the the health and target of by an unit targeted mob (meant to be used for tanks).

Melee stats Data Broker plugin.

A data broker plugin showing your longest fight and your current fight time.