I have an idea for a new game/art form. It's like etch-a-sketch, only you use your car windshield. First you drip some dirty water at the top of the windshield and you adjust the speed and direction of the car to control the path of the droplet as it attempts to make its way to the bottom. I think the optimal location to practice this game/art form would be the salt flats of Utah. One can incorporate split second decisions as to the velocity and direction one chooses without those pesky distractions such as curbs, pedestrians, houses and other cars.
So far, being limited in speed, location of turns, traffic rules and so forth, I've only been able to create a seemingly random rain spatter/dribble pattern. I'm sure with practice, determination, and a little time in the desert, I'll one day be able to make a gumby.