I'm sure someone, probably in Europe for a really low budget, has already done this. But, here's my idea: a 90-minute music video. It wouldn't just be one song; it would, of course, be many. But, it would be highly stylized, be interesting, have an interesting story, and be dialogue-free (or mostly so). It would definitely be possible to convey an intriguing plot through song; some music videos already do this. Just extend it out 30X and you've got a cool movie. From a commercial perspective, if you crammed in a few popular songs that didn't happen to suck, ticket sales probably would be decent, and the soundtrack would sell well. From an artistic perspective, as long as you didn't sell out too much it would be a really interesting project.