WowAce

Allows combined aura detection. motw + gotw, all 4 mage int buffs, etc. in one status.

Adds Friend and Guild options to the context menu of player units.

Save and send chat messages to many channels. Allows quick item and profession linking within your messages.

Displays the zone level ranage of the zone you are in and also gives you a suggest zone and instances to be in.

Automatically invites player from templates.

Armored man and paper doll durability modifier

Doodle

Desesperated announcing to clearly show the skillings of act inplay.

ChatHighlighter

Adds the toon name to the alert that your RealID friend has come online.

LCDs for WoW

Interface-central mount management

Adds aura indicators to unit frames

Make it easy to explain bosses in Raids.

Poppins

FuBar_MiniPerfsFu

Group interrupt cooldown tracking.

XP and Reputation bars

Automatically switches Profiles of addons when changing spec

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