WowAce

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

Watches your chat, flagging missplled words, and offering correctly spelled suggestions.

Collects Herbs, Mines, Gas Clouds, Archaeology, Treasure and Fishing locations and adds them to the worldmap and minimap

Gears skins for Masque.

LiteStep skins for Masque.

Onyx skins for Masque.

Serenity skins for Masque.

Simple and Advanced combined - Bartender4 ActionBar AddOn

Creates and manages secure Action Buttons

Replacement for ActionButton_Show/HideOverlayGlow APIs

Displays additional information for Mythic Keystone dungeons

Automatically leaves the global channels when inside an instance/raid and restores them when exited.

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

Good old LibTourist-3.0 for WoW Classic Mists of Pandaria

Inventory Management with virtual bags divided into sections.

AddOn development framework

Wowhead Data dump for GatherMate2

A friendly companion that remembers the chat.

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

Changes the look of the default UI