I'm a sucker for programming contests, and have been since high school.
I thought I would post here about one ongoing contest and one upcoming one.
First, the Intel Threading Challenge has already started. Essentially, it a little programming contest that is supposed to test your ability to program effectively for a large multi-threaded task. The "Master" section this year is writing a program to compute a simple and laborious graph theoretic property.
Second, the annual ICFP programming contest is right around the corner. Although nominally a functional programming contest, anyone can enter in any language. It's an super-fun, intense 72-hour competition. If you want to try to place, I recommend having a group of about 2–4 strong programmers. I won't be able to compete this year because of a scheduling conflict. :(