WowAce

Aperture

Keeps track of gold and cash flow across multiple characters

RaidSpy

Speeds up triggering actions such as items or spells by triggering them on key/mouse down rather than release

GearRating

A frame designed for each specialization of druid's watching their main power and important buffs/debuffs

PartyToGo

BigTrouble

NBuffBars

AltClick an item in your bag to add it a mail, auction, or trade frame, and alt-click to buy a stack if reagents.

A simple range indicator for optimizing Halo damage.

Monitor the remaining duration on your Mysterious Eggs and other perishable items.

FuBar_CraftTimersFu

Keep your pet fed

Augmented Virtual Reality. Draw and add markers in the 3d world.

Displays online friends.

Reverse Engineering will drill down and search your tradeskills for their elements

Draws some lovely 3D portraits in the standard Blizzard artwork.

T_Tracking

Adds item values to chat messages.