WowAce

XP and Reputation bars

Highly-configurable shield / absorb tracker.

Monitors for friendly deaths and announces them as in Myth: The Fallen Lords

Calculates optimal reforging for given weights/caps.

TradeStop

EQCompare

PT3Bar

A Data Broker display for combat statistics.

DeuceCommander

WQA helps you find world quest groups easily. Works after the 4/28 group finder changes.

AltClick an item in your bag to add it a mail, auction, or trade frame, and alt-click to buy a stack if reagents.

Gives detailed descriptions of particular localities, as zones or instances, and provides optional TomTom integration.

Tracks your keystones

Monk Brewmaster/WindWalker Priority and Buff/Debuff Tracking Tool

Heads Up Display with Player and Target Info

Considers an item against all the items you have to determine whether or not it is an upgrade

Adds your name to chat messages

Provide plenty of links

ShadowGreenLight helps you decide if recasting SWP/Corruption is worthwhile

Enables the filtering of items when you visit a vendor