WowAce

SmartyCatManaBar

Replacement for default Rune Frame and more.

A simplistic clock.

Keeps track of space left in your bags.

Broken in Midnight. I recommend MidnightFocusInterrupt instead.

A library to provide a clean dropdown menu interface.

Inspects all members of raid and saves in database, as well as lists people's dkp values

Tells you if you're buffed

Nihilum Raid Tracker, originally written for the EU guild Nihilum.

Sheppard

Database of Vendor locations for HandyNotes

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

YssGuildShop

FuBar_MicroMenuFu

Helps you decide which ability to use next according to priority you set

FuBar_RecZone

A Simple World of Warcraft Spam Filter!

Manages social information with a focus on main-alt associations.

Keeps track of your reagents for buffing.

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