WowAce

Instant SLAM! notification

Keeps track of your reagents for buffing.

ShadowGreenLight helps you decide if recasting SWP/Corruption is worthwhile

StitchUI

Displays online guild mates.

Calculates DKP based on Item Level

DarkCandy

Calculates optimal reforging for given weights/caps.

Adds talent specialization role status to Grid.

Swiss Army knife for instances, including player tracking, ignore buttons, loot tracking, notes, and more.

SwapMagic

Reno is a slash-command that can patch predefined options in a macro to change which abilities will be chosen.

Keeps track of space left in your bags.

Broker plugin to display player orientation

Friends & Guild Data Broker plugin.

A Library for stat conversion, calculation and summarization.

Monitor the remaining duration on your Mysterious Eggs and other perishable items.

GemCensus inspects people and records which gems they have socketed. Then displays which gems are the most popular.

Add-on that shows which mounts can be farmed this week

GetInLine