GIMP - GIMP is a multiplatform photo manipulation tool.
FotoFlexer - FotoFlexer is the most powerful online photo editor in existence.
Adobe Photoshop - Adobe Photoshop is a webtop application for editing images and photos online.
piZap - Free online photo editing software.
Krita - Krita is a professional FREE and open source painting program. It is made by artists that want to seaffordable art tools for everyone. Concept art. texture and matte painters, illustrations and comics.
Photoshop.com - Photoshop.