The Weekend Ray Tracer is a legendary set of exercises by Peter Shirley designed to enable anyone with basic programming experience to create a simple ray tracer in one weekend. You can get the books from here.
I use the WRT as an exercise in playing with a new language. I'm pushing this up to github incase anyone is interested and over time I will redo the implementations and rework the old for fun.
It's probably not that interesting to be honest, it's just me mucking about.