Various graphics programs to check out sometime. Not comprehensive, just some of the ones I hadn’t heard of yet.
GIMPshop, a re-skin of the Gimp to make the interface more Photoshop-like.
MojoWorld, a procedural fractal terrain/planet generator.
Natural Scene Designer, another terrain generator.
SketchUp, for easy “sketch-based” 3D architectural or mechanical designs.
Wizaerd’s Canvas Discussion Forum, for users of ACD’s Canvas.