I've searched around for different challenge sites, and most of them seem to be geared towards difficulty in problem solving logically, rather than trying to use your language of choice to do something you haven't used it for. Their center is around mathematics rather than function design. Some kind of point system for correctly solving challenges, or solving them the most efficient/smallest would be neat as well. Listed sites Project Euler TopCoder UVa Online Judge Challenges with Python Google Code Jam Programming Challenges Less Than Dot ACM's Programing Contest archive USACO problems ITA Software's puzzle page Refactor My Code Ruby Quiz