WowAce

Enable/Disable addons for your character in game

FuBar_OutfitterFu

FuBar_FuXPFu

Gives a score for your kit allowing easy comparison with others, also colour codes kit based on appropriateness for your level.

SmartyCatManaBar

ColaLight

Klappa

Allows you to prevent addons from sending and receiving messages.

Estimated time until current target will die.

Open inventory items with 1 button

Rep2 displays a message, which shows how much reputation you gained, and how much is needed until the next standing.

A tool to appraise, estimate, or judge your equipment against the equipment of others.

StarVisuals displays various data visualizations

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

VitalWatch

Building a Better Mailbox

WhiteboardNG

Pet Theory

Cartographer_Stats

Displays events from Calendar for upcoming week in tooltip.