WowAce

Death analysis tool

Track all threat redirection ability transfers and cooldowns (Misdirection and Tricks of the Trade).

Try on different gear and see their total stats and their differences. In short, an ingame CT-Profiles-like addon.

Raid Frames using the oUF framework.

Fires events whenever a raid member "fails."

Open all your mail

Shows your standings with the factions.

Reports in raid chat whenever a raid member "fails." /EnsidiaFails to configure.

Kaliban's Class Loot List Star Display

Threat reactive nameplates for TidyPlates.

Barks at you when you target a crowd-controlled unit

Shows class colors on player nameplates and names

FuBar_VampwatchFu

Tracks vulnerability debuffs on multiple mobs

Good old LibTourist-3.0 for WoW Classic Mists of Pandaria

Keeps track of quests.

Shows the mirco menu and game menu in a clickable broker tooltip. Also shoes fps and latency.

A library to help with localization of Zones.

Mutes various chat related annoyances while in capital cities and instances.

Dropdown library for Ace3 options, extensible to other options formats. Works ok.