The one I found most interesting was the GeoDart Game; this allow the user to place a series of points on the map and create a geographical game.
So far I have created two GeoDart games; both based on Football and one of them has been featured on the umapper blog.
I am working on a couple more that are more walking related.
Here are the two GeoDart Games.
To play it's best to open the map out to full screen by clicking the box in the top right corner.