WowAce

Announces Mage Spells in chat.

Tracks vulnerability debuffs on multiple mobs

Warnings about tanking specific abilities

Adds predicted lists for spells while the user types

Allows you to browse your clients database

MobHealth

HiveMind

Shows where the equipment of inspected users or yourself is from.

Adds unreal tournament style sounds to PvP encounters.

Shows current/dot cast haste values

Toggles WoW to the forground on events.

Review any raid or party members recent incoming combat along with health level.

HunterAEP

Dynamic item DKP calculation

MainAssist

BuffMe

You've got mail!

Klappa

Shows Chat as Combat Text

Embeddable chat throttling library with traffic shaping and priorities