Or if you get on a creative bent, try
Universe Image Creator - diard software, has a free space image creator, and a spendy one. Handy for skies, etc.
Terragen- a landscape creator, good skies, good water, but no plants (at least not the last time I saw..;) also free, at Planetside site
Geofrac(?)- there are several fractal programs out there for free..I think this is one. A really nice one is called (I think) Xeno dream, and can actually export models, but they want buckies for that..:|
Project Dogwaffle, and The Gimp (gimp.org, Dogwaffle I don't have memorized..;) Free paint, and free 'photoshop clone', good for effects, cropping pics, layering, etc..could turn out handy..;) Have fun

I wish I'd said that.. The Staircase Wit

anahl nathrak uth vas betude doth yel dyenvey..;)