DARPA (Defense Advanced Research Projects Agency) is one of those super secret government agencies that dreams up wild new technology for the US military, so it's kind of a shock to discover that their latest project is a video game that anyone can download and play.
ACTUV Tactics is based on a real DARPA program to develop new ways to hunt down enemy submarines, but the really cool part is that your tactics and results can be sent directly to DARPA for analysis. DARPA thinks that there must be some really clever kids out there who could come up with some sub hunting tactics they never thought of, and they plan to use crowdsourcing with this game to learn them.
While the graphics aren't exactly going to give Halo 3 much to worry about, you've got to admit that it's pretty cool to have your results graded by DARPA. The site makes it clear that they don't keep any identifying info about who is playing, but you've got to wonder if they will attempt to track down and hire anyone who does a particularly amazing job.