WowAce

Show a texture on demand

Mutt (Macro Update Target Tool) provides slash-commands that can patch the predefined targets in your macros.

PreferredItems

Aura alarm.

FuBar_ExperienceFu

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

Ironi's Encounter Event Tracker

Displays information about the current zone on the World Map

Keeps track of time played and rested XP across your characters.

NextStep

A small checklist for raid (de)buffs and who brings what.

Raid Cooldowns

Detects specific CDs and spellcasts

A library for PvP and Battlegrounds

Shows your standings with the factions.

Scorchio!

Adds your name to chat messages

Tracking and ranking of dps/hps in a guild.

Filters AFK and DND messages after you've seen them once.

Gathers statistics on certain chance-on-use spells, also known as procs.