WowAce

Track of your tradeskills across characters, create small buttons for them and track cooldowns.

LCDs for WoW

ItemSync the happy item gatherer and toolkit.

Keeps track of current money and all your characters on one realm.

MiniPet, Always keep your little companion with you, based on the work of Carra.

Tankalyze

Adds mob patrol paths to your map.

Configurable Castbars

FuBar_HonorFu

Displays Pet Info for Hunters and Warlocks. Also keeps track of Stables and Pet and Demon skills.

Track all threat redirection ability transfers and cooldowns (Misdirection and Tricks of the Trade).

Collects Herbs, Mines, Gas Clouds and Fishing locations and adds them to the worldmap and minimap

Aura alarm.

Detects specific CDs and spellcasts

tracks and share quests between your party

HUD that you can tweak the way you want.

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

Allows the user to preview and track their progress in the collection of various transmogrification appearance sets

Combination of Titan LootType and Roll - stripped down and cleaned up.

Shows simple Buttons for your Cooldowns :)