WowAce

Provides a virtual keyboard of extended-ASCII and Unicode characters which can be inserted into text areas.

Teknicolor_tab

Caser

A mod to filter the Trade chat, shunting it to a seperate chat window if it exists (chat window is OMGWTFBBQ).

Blocks all whispers except from people in your guild and friends list.

Provides search functionality to the chatframes

AutoGratz

A friend in need is a unconversable robot friend.

FailBotSpam

Library that provides a timestamp that is equal across clients' timezones and system clocks

Show everyone how much you care

Addon to manage WoW titles.

Two-way radio functionality for IC communication

LFG Settings Saver

Adds the ability to send mass mails to guild ranks.

AB

An Addon to make give stock messages based on location or target.

Automatically promotes a group of players to calendar event moderators.

Makes raid rolls easier!

Enigma