WowAce

Announces results of readychecks to the raid/party, installs "/rc" alias, shows rc timer bar

Warnings about tanking specific abilities

Constructs a SimC export string for an item without equipping it

A fully featured library tracking all ongoing absorb effects

Stable

Makes your item stats shine!

Warns you with sounds when you gain different shaman spells.

Lists Pots and Herbs you got on all chars and allows you to specify color coding

KC_Items

ezIcons

Notifies you of experience gains

Shows a circle on the minimap to indicate spell range

Shows where the equipment of inspected users or yourself is from.

Displays info about who rolled Need/Greed/Pass on items that are currently rolled for

DarkCandy

Wrapper to convert HealComm data from 3.0 to 4.0

TouristLib

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

Does a /who search of multiple dungeons.

Announces ooze kill instructions during the Yor'sajh encounter in Dragon Soul. Highly customizable with numerous helpful feat...