Check out this awesome Lego bowling game by Flickr user Nxtguy. After a ball is rolled, a sound sensor detects when the ball hits the pins and uses a light sensor to check how many pins have been knocked down. After the frame completes, a NXT servo connected to a pair of linear actuators resets the pins. A work in progress, it is currently impossible to get a strike, though you can get a spare.

See the Flickr set.