WowAce

Chat addon, filtering messages and UI changes

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

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

Give whispers an instant messenger feel.

Shared handling of alternate identity data between addons.

A friendly companion that remembers the chat.

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

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

Redirect character errors, system messages and information messages.

Lightweight Chat Improvements

Set and manage character notes that are displayed in unit tooltips and /who results.

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

A blizzard group finder replacement

Blocks Chinese Chat

Manages social information with a focus on main-alt associations.

Says random things in chat when casting any spell or ability. Type "/ss help" for the user's manual.

Displays online friends.

Tracks SendAddonMessage Spam

Automate Your GDKP Auctions, Bids, & Payouts

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