Have a look at what Michela Ledwidge is doing at ModFilms, a site for people to do remixes of films. She is also working on a ‘massively multiplayer online movie’ called Sanctuary. It is described as follows:
Sanctuary is an experimental sci-fi short due for release 2006. The project, now in VFX POST PRODUCTION, is both a pilot for an ambitious feature film and a world-first exploration of production and distribution methods aimed at giving audiences greater empowerment through a next-generation story format.