Inkscape - Inkscape is a free, open source professional vector graphics editor for Windows, Mac OS X and Linux.
Vectr - Free vector graphics editor. A simple yet powerful web and desktop cross-platform tool for everyone.
Blender - Blender is the open source, cross platform suite of tools for 3D creation.
PixaPal - Create videos, graphics and documents online
Sculptris - Sculptris: Enter a world of digital art without barriers.
GIMP Online - Powerful graphics editor in the cloud