Topcoder

Anyone here compete in it? Perhaps not since they don't support scheme(supported languages are c++, java, c# and partially vb(some of the 'harder' problems will time out if you do them in vb)). I find the single round algorithm competitions pretty fun when they are at a reasonable hour, though weather its a good test of programming skills is debatable.
Website is topcoder.com/tc if you didn't know about it.

You can compile Lisp code to Java or C.