WowAce

Keeps track of HoTs, DoTs, Buffs and Cooldowns. With audio and text alerts to refresh them.

Shows class colors on player nameplates and names

Regain that wasted space!

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

Threat reactive nameplates for TidyPlates.

Shows your standings with the factions.

Tracks vulnerability debuffs on multiple mobs

Kaliban's Class Loot List Star Display

Reduces interface tedium by doing the little things for you.

A Simple World of Warcraft Spam Filter!

Show what quests have changed

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

An Atlas Plugin that displays arena maps.

DKP system for all guilds in the Banana Republic.

A library to help with localization of Zones.

Raid loot tracking and text generation

Violation

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

Displays information about the current zone on the World Map for WoW Classic Era

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