The sequel to the cult hit Donnie Darko had some viral marketing to promote it. Some pretty cool stuff.
PS- I saw the movie. Sometimes it felt like a remake and not really a sequel. But it did do a better job at explaining what "the end of the world" means, and did see the return of Frank the Bunny... kind of. Definitely worth a rental if you have nothing better to do on a Sunday afternoon.
Video footage of a strange death
Popular conspiracy theorist's stance on what happened
Video response to the theory of the previous poster