WowAce

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

Death reports

Shows skills in a tooltip and allow them to be used. Also keeps track of Cooldowns.

Simple Spell Alert

Heads Up Display with Player and Target Info

item2phpBB

Rewrite myBindings. An enhanced key bindings interface.

This will keep track of how much you have paid per item in your inventory. Only one of (Auctionator, Auctioneer, AuctionLite,...

Keeps track of your reagents for buffing.

Visual loot monitor

Dynamically atering layout in raid environment (Tanks, Ranged / Melee DPS, Healers)

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

StatStain

Add-on that shows in a unit tooltip window a number of killed mobs of the same kind

SanityItemCache

Cartographer_Treasure

Keeps track of gold and cash flow across multiple characters

Customizing your buff display

Tracks interrupts

FuBar_MicroMenuFu