PhotoDemon - Lightweight portable BSD licensed photo editor for Windows focused on performance and usability.
Photoscape - high quality photo editing software, that enables you to fix and enhance photos.
PhotoFlare - Quick, simple but powerful Cross Platform image editor.
Pixelmator - Pixelmator is an image-editing application for Mac and iPad.
PixBuilder - Free Photo Editing Software for PC
Pixlr - Pixlr® makes it easy to transform everyday images into stunning works of art.