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!
It's been said many times that there is no such thing as an original idea, that everything created in the world is a derivative of or inspired by something else. For the most part I think this is true but it also depends on how you define originality. If you're a purist, which is sounds like you are, then originality is extremely hard to achieve. I mean, the very essence of inspiration means being inspired by the idea, words or work of someone or something else. I think a better way thing to strive for is creating something useful, something that brings people joy and/or improves their lives. In the end, if you're work is derivative of something else, who cares, as long as it's not plagarism and you've made meaningful changes or improvements that differentiates your product from the inspiration - then originality starts to not matter so much. Don't start by trying to reinvent the wheel - maybe start out by trying to make it better or more useful for a particular group of people.