WowAce

Shows activity for hidden ChatFrames by making their tabs flash.

Simple language selection for Data Broker

Filters AFK and DND messages after you've seen them once.

Keeps tracks of /rolls.

MiniChat

Displays friend notes in unit tooltips, at logon, and in /who results.

Tracks and announces interrupts (eg. Hit/Miss/Immune) and is also able to track and report "wasted" interrupts (those which d...

Shows Chat as Combat Text

Provides bang-whispers for your professions.

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

Displays online friends.

Allows customisation of login/logout system messages.

TwiCo

Customize the appearance of the chat bubbles.

Allows for easy congratulating when someone earns an achievement.

Adds item values to chat messages.

BossWhisperer

RS_ClassColors

Crowd-control monitor

Lists and/or reminds people missing flasks or food buffs at every ready check.