PhotoFlare - Quick, simple but powerful Cross Platform image editor.
Inkscape - Inkscape is a free, open source professional vector graphics editor for Windows, Mac OS X and Linux.
PixBuilder - Free Photo Editing Software for PC
Sculptris - Sculptris: Enter a world of digital art without barriers.
PhotoDemon - Lightweight portable BSD licensed photo editor for Windows focused on performance and usability.
ShapeShop - ShapeShop is an advanced and professional 3D design and modeling application that comes with an easy-to-use and user-friendly interface.