If you have time to spare, here’s something you should try out – it’s a "game" called Line Rider:
The aim of the game? Well… there isn’t one really – basically what you do is you drawn a 2-D landscape using the pen tool and when you hit "play", a cartoon character (i.e. the Line Rider) rides a sledge down the landscape you just drew.
I have to say, this game is annoyingly addictive – I spent 3 hours playing on it last night!
Anyway, while you are downloading the game, you might wanna check out this video of what someone did with it: