Diaspora is one alternative. I had the pleasure of meeting the founders and they are great guys. Their philosophy around social networks is that its your information and you should be able to control it, take it with you and share it on your terms. It is still in the Beta stage so if you would like to join, send me your email address and I'll send you an invitation to join so you can check it out. Another one, which is mobile only, is Colors. It's photo based and uses location and frequency of interaction to manage what information you share with whom. You can find it on the iTunes app store. Hope that helps!