Ray-tracing
A ray-tracing program creates an image by simulating the method that our eyes receive images (without all that tiresome focusing), but in reverse. If you want a better explanation, see the wikipedia article. Ray-tracing allows the creation of photo-realistic images (although the field of focus is infinite, so the images are rather better than a photograph from that point of view).
I've recently started experimenting with this method myself, using POV-Ray, and as it is almost perfectly suited to my artistic style, and allows me to put my hard-won geometry to some, if not quite practical, at least aesthetically pleasing use I think I'll keep it up as a hobby.
As it stands, I have created only one full-scale composition, the rest of my time being spent mastering the (very) basic techniques - mainly drawing and manipulating primitives.
The Sheep And The Goats
My Work in Progress (aug 2006):
Abhorsen (WARNING: Large number of BITMAP files
- while I intend to convert to jpg once the project is finished, currently all
the 'work in progress pictures' are in their original format)