WowAce

Makes those pesky garrison animations go away.

OneBag is a replacement for the default game bags that combines all the bags into one frame.

Enhancer

A library to handle rearrangement of blizzard's frames when bars are added to the sides of the screen.

Guilder brings common guild-raid tasks together in one convenient place.

Insanity resource tracker for shadow priests.

Fade Blizzard Raid Frames

Allows customisation of login/logout system messages.

Shows the minimum durability of equipped items on the stats frame.

Hemlock

Announces interrupts in the chat

Better quest log and tracker

Powerleveling guide framework

AspectsBar

AceBuffGroups

A customizable casting bar replacement for TBC Classic & Classic WoW

Disease Tracker for Death Knights.

Simple and rich Death Knight rune customizations

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

FuBar_RecZone