MiniLight: a minimal global illumination renderer (re)written in Scala, OCaml, Python, Ruby, Lua, Flex and C++ : http://www.hxa.name/minilight/
I think it would be interesting to have a D version and compare for the float performance and maybe even lines of code. There is another similar "benchmark" here: http://lucille.atso-net.jp/aobench/ (from reddit) I'm too much of a D noobie myself to attempt this.
