WowAce

Tracks profession specific cooldowns and items across all your characters

Need Greed window for EPGP lootdistribution.

Makes the Blizzard options frame movable and resizable

AutoMagicly clicks though Daily Quests, and Turns them In.

Combine

FuBar_FarmerFu

eePanels

Powerleveling guide framework

Note + rep tracking for players, with guild data sharing.

A customizable casting bar replacement for TBC Classic & Classic WoW

Makes those pesky garrison animations go away.

Fade Blizzard Raid Frames

Cartographer_nnTrainers

GonffBar

Control screenshot format and quality via LDB displays

Disease Tracker for Death Knights.

Check the consumable usage of your raid

Rewrite myBindings. An enhanced key bindings interface.

Library supporting plug in filters.

Various libraries based on LCD4Linux, offering users lower-level UI customizations.