Might not be elegant, but here's an example of a very simple little ray tracer I wrote in perl (it only renders mirrored spheres and checkered planes)...

http://sleepingsquirrel.org/ray_trace/trace.txt

...it parses a POV-like scene file...

http://sleepingsquirrel.org/ray_trace/test.pov

...and produces a *.ppm file on STDOUT...

http://sleepingsquirrel.org/ray_trace/out.png

For those of you who don't know perl, you can look at the Haskell version...

http://sleepingsquirrel.org/ray_trace/trace.hs

I've always been meaning to write a Scheme version, maybe this will push me over the edge.