Spine - Spine is 2D animation software designed specifically for software and game development.
DeviantArt - deviantART was created to entertain, inspire, and empower the artist in all of us.
Synfig Studio - Just another WordPress site
Brush Ninja - Hand-drawn Animated Gif Creator
Unity 2D - Unity 2D is a powerful and feature-rich game design solution built from the ground up to fulfill every basic and advanced need of the developer.
pixiv - pixiv is an illustration community service where you can post and enjoy creative work. A large variety of work is uploaded, and user-organized contests are frequently held as well.