WowAce

ClosetGnome_Switcher

Cartographer_QuestObjectives

Keeps account of attendance and loot for raids, parties, bgs, arenas and solo for questing.

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

FuBar_HonorFu

Enhancer

Keeps track of durability and pops up a dialog to repair when you go to a vendor who can.

Helps you automate selling stuff

Keeps track of HoTs, DoTs, Buffs and Cooldowns. With audio and text alerts to refresh them.

Reno is a slash-command that can patch predefined options in a macro to change which abilities will be chosen.

Manufac

Alternate Rune Display

Smooth group roll frames

Angry Raid Points Client

Adds Outfitter set filters to AdiBags.

Animated target indicator

Regain that wasted space!

adds navigation buttons to Encounter Journal

A library to help with localization of talent trees.

Adds achievement reminders to BigWigs