Rubinius : Use Ruby™ - I'm not a big Ruby fan, but Rubinius (Ruby-in-mostly-Ruby) has been released as version 1.0. And the various projects to bring Ruby to a mostly Ruby-based platform with LLVM underneath still make me envious. I would love to have something like that for Python ... (yes, I know Unladen Swallow and PyPy - but both are still miles away from a serious version, unfortunately)