ResearchGate is a network dedicated to science and research. Connect, collaborate and discover scientific publications, jobs and conferences. All for free.
ThinkUp is a free, open source web application that captures your posts, tweets, replies, retweets, friends, followers and links on social networks like Twitter and Facebook.
With ThinkUp, you can store your social activity in a database that you control, making it easy to search, sort, analyze, publish and display activity from your network. All you need is a web server that can run a PHP application.
mspro will channels statt circles bei google+ (einerseits ja, andererseits immer noch zu kompliziert, konversationen werden schwierig weil unklar ist, wer was gelesen hat oder haben könnte, also worauf aufbaubar ist)
D. Liben-Nowell, and J. Kleinberg. Proceedings of the twelfth international conference on Information and knowledge management - CIKM \textquotesingle03, ACM Press, (2003)