Maybe this is too small scale to be relevant, but i recently designed a site for a rockabilly clothes webstore, with a complete panel of tools: myspace (traditional friending, exchanging thankyous), facebook (fanpage & paying ads), google ads and twitter... And since day 1, myspace has been the nr. 1 referrer (to such an extent that bandwidth quotas exploded, and my customer had to upgrade their hosting plan). So I would say that for some niches, myspace is still nr. 1. Also, coding css for myspace is really fun, if you like a good challenge