WowAce

Fancy up the ExtraActionButton frame

Good looking, smoothy and helpful nameplates

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

Library to help with querying unit talents.

ItemPriceTooltip

LilSparky's Workshop mod for Trade Skills

Clean looking square minimap with many options.

Fixes UI bugs

Enhances the StackSplitFrame with numbered Buttons, a '1-Click Mode' and a 'Auto Split Mode'.

mHud

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

RBM

Collects, analyzes and presents information about the virtual economy.

Library supporting plug in filters.

Client for MagicDKP which handles standby calls and bidding on items.

StitchUI

Assistance to the dance during Dread Spray

Sanity2

A library for PvP and Battlegrounds

Avion