I joined myspace as a free website for publicising music and it worked well for a while. The myspace music sites were much friendlier to musicians than the Facebook sites, but non-musicians seemed to gravitate to Facebook and so I moved there too. I find that if I advertise a gig on Facebook, I'll have a full house, where running around sticking up posters was a pain and not even as effective.
One trouble with Facebook is that you can't really post tunes and expect them to stay there. They just scroll down outa sight.