WowAce

Displays bars depending on your professions

Tracks Black Market Auction House auctions.

Shows skills in a tooltip and allow them to be used. Also keeps track of Cooldowns.

A library to try to guess a level of a player.

RaidHelper

Piece of mind by being one with your class.

Automatically sells low quality gray items and selected white items to the vendor.

Sheppard

Cartographer_Mailboxes

Lets you drag UI frames around

On login, displays changes to your guild since the last time you logged in.

TableTopLib

FuBar_TrainerFu

Adds an additional spell alert if you have more than one charge of a buff that is normally tracked by the in game spell alert...

Simple Spell Alert

Add TomTom Waypoints for Flight Masters in classic

Welfare Epics

Provides the ability to suppress specific spellcasts like "Deaden" from your casting bars.

FuBar_KTMFu

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