WowAce

Tells you the Tiller, what food they like, and if you have fed them today for the quests A Dish for ...

Automatically and immediately cancels all in-game cinematics and movies

Objective Tracker

Toggles WoW to the forground on events.

Cryolysis 2

Pins on the World Map for quests you have not completed yet

AutoMagicly clicks though Daily Quests, and Turns them In.

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

Adds achievement reminders to BigWigs

Embeddable chat throttling library with traffic shaping and priorities

Announces interrupts in the chat

Simple quest item bar.

Keeps track of current money and all your characters on one realm.

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

A Mount and Companion manager

VitalWatch

New/Old BG indicator, Join by ID, Quick Leave Queue, etc.

Target Debuff monitor. Stacking aware, giving current and potential debuff status.

Makes the Blizzard options frame movable and resizable

IncomingHealsLib