WowAce

Allows communication to be shared across realm through Battle.net.

Helps to track outgoing mails

A PitBull4 module which shows an arrow that points to raid members

Voyeur

ClassColors

TradeStop

Saves contents of your guild bank and sends/receives updates over the addon channel

FuBar_CombatTimeFu

Quixote

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

Assister

Embeddable library to track raid/party roster

Records mail when visiting the mailbox to make keeping track of mail and expiration dates easy.

Allows customisation of login/logout system messages.

Shows a frame to track your debuff on Malygos in phase three.

Aspect checker addon for Hunters.

Bars showing amount of buffstacks

Puts a timer in /yell when you get Unbound Plague during the Heroic Professor Putricide encounter

Light-weight enhanced casting bars

Manages the scanning of the auction house in a reliable an efficient manner.