WowAce

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

Auto roll greed, need, pass or manually roll on items.

Mutt (Macro Update Target Tool) provides slash-commands that can patch the predefined targets in your macros.

AceBuffGroups

Simple display and management of Away / AFK / Busy / DND status via broker or minimap

Litmus

A customizable view of friends and guildmates.

Alternate Rune Display

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

Tracks profession specific cooldowns and items across all your characters

Adds Outfitter set filters to AdiBags.

BarAnnounce3

tekKonfig

HunterAEP

Hemlock

Library handling communcation for Magic* addons

Transcendence Monitor for Monks

RoleCall allows you to easily see the talent specs and roles of everyone in your group.

Tracks the precise arrival & departure schedules of boats and Zeppelins around Azeroth and displays them on the Mini-Map and ...

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