WowAce

TrainingWheels

DebuffEnough

Replacement for the default nameplates.

Adds two icon indicators to each corner (total: 8 icon indicators).

Tracks Black Market Auction House auctions.

Displays performance-related stats for shadow priests.

Test whether the player can really dispell a buff or debuff, given its talents.

For Developers (of Addons which uses LibWho-2.0): show queues and queries in realtime

Should I send that recipe to my alt?

Outdated! Please use 'XLoot', available on Curse and WoWI

Display an arrow that points to a raid/party member anchored to raid frames

Shows you which bosses you've killed next to the raid finder frame.

BossWhisperer

EyeCandy

Adds pipes which can control arbitary other statuses (like toggle status on key or "in combat"-state).

Helps you automate selling stuff

RBM_AbilityWatch

Embeddable chat throttling library with traffic shaping and priorities

Dropin replacement library for SetBackDrop

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