Fenetre App - Picture in picture for your mac.
Scary Camera Effects - Creepy and artistic photo manipulation, 20+ filters
Polarr Photo Editor 3 - The most powerful photo editor in the web.
Dreamscope - Make and share 'deep dream' images using dozens of supplied styles or your own.
Pixelmator - Pixelmator is an image-editing application for Mac and iPad.
Duotone - Convert any photo to a duotone in seconds