Google Maps + Risk
Play Risk with your friends without having to pull out the old gameboard. You kind of have to play with a friend or two as there is no AI or network multiplay (but there may be these features in the future, according to the site.) If you really want to, I guess you could just play with yourself... I meant play GMRisk with yourself, pervs!
Update: Looks like the site got hit with a cease and desist order from Hasbro over copyright issues for Risk and has been shut down. C'est la vie.