DeviantArt - deviantART was created to entertain, inspire, and empower the artist in all of us.
Inkscape - Inkscape is a free, open source professional vector graphics editor for Windows, Mac OS X and Linux.
Brush Ninja - Hand-drawn Animated Gif Creator
Sketch - Professional digital design for Mac.
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.
Affinity Designer - Professional creative software, exclusively for Mac.