Social Media is growing daily, so it's good to think about your own social network.
What I have recently found on this:
Elgg is an open, flexible social application engine, designed to run at the heart of any socially-aware application. Building on Elgg is easy, and because the engine handles common web application and social functionality for you, you can concentrate on developing your idea.
Sounds promising, looks even better but it is testing yet, so need to check later - I think it's really worthy thing.
2. Boonex -Dolphin
They call it "Smart community builder" - you can build any social network you wish - just your imagination:) Yes, but I've heard there are some bugs in the soft and then you should pay for their support...
Still soft is free, features are promising. Not bad to try:)
That's all about this topic till now, but it's just the beginning.