GIMP - GIMP is a multiplatform photo manipulation tool.
RealWorld Photos - RealWorld Photos is an free portable photo editor for Windows.
Pixlr - Pixlr® makes it easy to transform everyday images into stunning works of art.
Online Image Editor - Online editor for images and animated gifs with multiple effects and tools
Photoscape - high quality photo editing software, that enables you to fix and enhance photos.
SoftColor PhotoEQ - SoftColor PhotoEQ makes color correction, image editing and color management tasks simpler.