WowAce

Displays online guild mates.

Assessment

Adds various information based on PeriodicTable to item tooltips.

An extension to the default WoW Unit Frames.

Cryolysis 2

XRS

Keeps track of your top hits, heals, criticals, etc.

MorgDKP

Queing of /who and SendWho() queries and a much better interface (see docs), with gurantee to be executed & callback.

Keeps track of your current location.

Watches your chat, flagging missplled words, and offering correctly spelled suggestions.

CT_RaidAssist style raid frames

Adds a status to Grid for debuffs applied by Raid Bosses.

Additional information about player spells.

Tooltip scanning library.

Tracks the HoTs you cast.

Display Cooldown Count of Spell Icon and Item

Collects Herbs, Mines, Gas Clouds and Fishing locations and adds them to the worldmap and minimap

Displays online friends.

Antagonist