There is no evidence *at all* that free music on the Internet is an effective (i.e. successful career building) marketing tool. There have been no blockbuster successes that have come from, for example Garageband availability. I don’t think you could even count more than a handful – if that – Internet-based artists making a living from music. I believe several of the American Idol contestants have been on indie music Internet sites, but you cannot attribute their success to the Internet.
Why Does Everything Suck on Free Music