I used to use MySpace but it became a cesspool of others spamming my page. I've just given up on utilizing the social networking sites since the amount of time needed to keep it running properly just isn't worth it.
Interesting - Myspace certainly has come to be seen as a spam site recently for sure. We've used bookmarking sites like Stumbleupon, Mixx and others, combined with Wordpress blogs and Squidoo...along with the video sharing sites...and had pretty good success.
For bands, MySpace is king. For films, haven't tried it, buy the MySpace IndieTalk page gets a lot of views and drives people here. For social networking I have no idea. I don't network socially, only for business.