WowAce

VendorSearch adds search features when buying items from any vendor

Adds aura indicators to unit frames

Heal and decurse by clicking on customizable raid/party unit frames

A raid buff tracker

LDB data source displaying character stats

Sets you to DND when you fight a boss, and some other crap.

Communicates with guild members for their positions on the world map

A loot distribution addon meant to improve master looting during raids.

EQCompare

ImprovedTargetFrame

Adds cooldown timers to your trinket procs

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

Adds a confirmation dialog when crafting Bind-On-Pickup trade skill items

Smooth combat HUD based on ArcHUD2

ItemEnchantApplication

Allows you to create icons, which can be customized greatly by user's input. CiR is more than just the usual cooldown tracker.

Bars showing amount of buffstacks

A simple, zero config, trash item seller

Allow rule based automatic rolling on loot.

Displays a grid of guild ranks versus permissions.