I had a lot of fun running a low-prep one-shot zombie apocalypse game extensively drawing on google maps and streetview - looking them up ad-hoc during the game as players explored real locations.
I've also thought it would be kind of funny to have a game where they players start out as themselves, at the start of the game, and then describe myself going to the door to check on some banging. I get eaten by a zombie and we go from there.
