WowAce

Officially the original source of knowledge of where things are in Draenor during Warlords, in HandyNotes

A skinning engine for button-based add-ons.

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

Library to check whether an item is equipable / appropriate for a given class

Does stuff for sachmo

Replacement for ActionButton_Show/HideOverlayGlow APIs

Uses various methods to scan your surroundings for rare or specified NPCs.

Estimated range display. Type /rangedisplay for config

Creates and manages secure Action Buttons

An intuitive keybindings library.

Another HUD addon

Ackis Recipe List is an addon which will scan your trade skills and provide information on how to obtain recipes. It works fo...

Modular casting bar.

A library allowing for easy creation of graphs

Core module for Loot and Looting-related UI improvements

Library of data about what items tier tokens can be turned in for

Postal: Enhanced Mailbox support

"Debug" code free since '93!

Allows you to view all items from all your characters on the same account, when-ever and where-ever you want.

Shared handling of alternate identity data between addons.