A simple raytracing program I wrote back in ~2007. So far, the program is only useful for generating pictures of basic, slightly out-of-focus cubes. That said, they look pretty cool. I haven't touched this project in years but the basics may be useful for someone starting out writing their own raytracing program.
Here's a few of the cooler looking images I was able to make using the program:
Closest I got to something that would be considered an actual render
Test image showing a wall checkered with black boxes and holes
Backwall renered as a checkered test pattern. Shown here with what appears to be an off-by-one error