WowAce

Provides info about spell teaching items.

Meant To Do That

Tools to easily compare gear among party members.

bgsounds

Configure which layout or profile to load on entering a zone

Shows on the minimap where to fetch Finklestein's reagents

Database of reforging IDs

Check for unenchanted and ungemmed items

CurseBar

Automatically calls ForecQuit() right before you are AFK-disconnected to quit wow instead of going to the character selection...

Adds TargetIcon status to Grid2 (player / player-target).

ElectrofluxTextronator

Small Diamond Icon Pack for Cartographer

HuntersMark

A library to provide a way to easily create controls for Blizzard's options system

LibMindReader

LibSpecialEvents-Aura-3.0

Notifies you when you get aggro.

Shows how many epics (and other qualities) you are wearing

Shows Jukes and Interrupts