WowAce

Scan for rare mobs so you can find them and their loot

Chat addon, filtering messages and UI changes

Tracks Raid/Instance/World Boss lockouts for all your characters, daily/weekly quests, currencies, trade cooldowns, and more!

Give whispers an instant messenger feel.

Lightweight Chat Improvements

Prat

A friendly companion that remembers the chat.

Shared handling of alternate identity data between addons.

Watches your chat, flagging missplled words, and offering correctly spelled suggestions.

A blizzard group finder replacement

Enables multi-line/unlimited-length pasting of text or commands into WoW

Redirect character errors, system messages and information messages.

Configure triggers to send messages to your raid team such as timers, rotations, and health/power based triggers. Raid smarter not harder.

A Simple World of Warcraft Spam Filter!

Loudmouth

A Collection of Automations and Interface Tweaks.

Mutes various chat related annoyances while in capital cities and instances.

Creates virtual cyphered chat channels over guild addon communication channel.

Displays online friends.

Displays online guild mates.