WowAce

Improved Quest Tracker

Captures chatframe Tradeskill Links for later reference in an easy to read format

Uses guild notes to add alts' main names to chat windows and other places

Allows raid leaders to view information on raid or guild member equipment information

Enables user defined sounds for Party, Guild, Raid and Custom Channel chat messages.

A clone of the FailBot mod. Announces raid member failures such as "Player1 fails at frogger"

Simple language selection for Data Broker

Allows you to prevent addons from sending and receiving messages.

DreamChat

Simple display and management of Away / AFK / Busy / DND status via broker or minimap

MonkeyPirate

Shows activity for hidden ChatFrames by making their tabs flash.

Enables cooldown notification between players and allows party members access to each-others spell books.

A customizable view of friends and guildmates.

Adds your name to chat messages

Automatically leaves the global channels when inside an instance/raid and restores them when exited.

Automate Your GDKP Auctions, Bids, & Payouts

Enables you to see Chinese, Japanese and other languages in game

Allows customisation of login/logout system messages.

Shows Chat as Combat Text