WowAce

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

Chat addon, filtering messages and UI changes

Give whispers an instant messenger feel.

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

Shared handling of alternate identity data between addons.

A friendly companion that remembers the chat.

Redirect character errors, system messages and information messages.

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

Lightweight Chat Improvements

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

Displays online guild mates.

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

A blizzard group finder replacement

A Collection of Automations and Interface Tweaks.

Displays online friends.

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

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

Plays sound when a ready check, LFG queue, battleground queue, or world battleground queue pops even if you have sounds turne...

A simple slash-command-based addon for querying item information from the Blizzard servers via ItemIDs and SpellIDs.

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