WowAce

In-game EPGP guild helper, supports standby, main/alt shared pools, minEP, offpecGP. Fixed price list with progress multiplier.

Makes the default frames moveable via simple drag and drop

Chat addon, filtering messages and UI changes

AddOn development framework

Tracks Raid/Instance/World Boss lockouts for all your characters, daily/weekly quests, currencies, trade cooldowns, and more!

Auto repair + shows durability.

A library to provide a markup syntax

A library to provide unit-oriented tags to LibDogTag-3.0

Tracks herbs/ore/items that can be broken into component pieces

Library of compressed itemid sets.

Inventory Management with virtual bags divided into sections.

Shows where the equipment of inspected users or yourself is from.

Another HUD addon

Death analysis tool

Shared handling of media data (fonts, sounds, textures, ...) between addons.

Redirect character errors, system messages and information messages.

Displays additional information for Mythic Keystone dungeons

Quality of Life Tools for Group questing/leveling

Tracks rare drops, including companions and mounts

Compact rune and proc display for Death Knights.