That Prequel thing looks promising @blackdutchie, I've always likes that concept of readers determining the fate of a story, like in Problem Sleuth for example. (Not a fan of fake ones like homestuck though.)
Here's a couple of awesome webcomics that both have the same premise, where the movie that they're based on is just a made up thing by a gamemaster of an RPG
http://www.darthsanddroids.net/episodes/0001.html (Star Wars episode 1, really makes me wanna start rpg'ing again)
http://www.shamusyoung.com/twentysidedtale/?p=612 (LotR, makes me remember what rpgs are really like :P)