Recount
DPS Meter. Tracks damage and healing output of everyone in your group or raid.
DHUD3
Displays your health/mana and target health/mana in an arc in the centre of the screen.
Shadowed Unit Frames
Allows modification of unit frames (player, target, party, etc.) including adding animated 3D portraits, custom sizing, and positioning.
Omen Threat Meter
Alerts you if you are about to pull aggro away from the tank; or, if you are the tank, lets you know if anyone is pulling aggro from you.
Prat
Adds time stamps to chat, enables mouse scrolling of chat, hides chat frame buttons, keeps chat history between sessions.
Bagnon
Consolidates all your bags into one customizable bag and allows you to see the contents of your bank bags as well as the bags of other characters on your account at any time.