WowAce

Shared handling of media data (fonts, sounds, textures, ...) between addons.

adds navigation buttons to Encounter Journal

Adds a button to the quest completion interface which allows you to auto equips selected quest Item after completion

FuBar_NinjutFu

Piece of mind by being one with your class.

ComboSounds

A Library for stat conversion, calculation and summarization.

SanityItemCache

Automatically generate and announce optimal spirit totem assignments during the Gara'jal encounter in Mogu'shan Vaults.

Speed plugin for any DataBroker display.

Quest information

Display bag usage on each of your bag slots.

PT3Bar

Display the global cooldown around your cursor. (+ other stuff)

Displays friend notes in unit tooltips, at logon, and in /who results.

Cartographer_Trainers

Battleground Timers in a HUD around the Blizzard BG status

Simple and rich Death Knight rune customizations

Heal and decurse by clicking on customizable raid/party unit frames

quick quest turnin and acceptance with a shared keybind