We came across a new set of libraries (API - application programming interface) called www.Elgg.org - which help you to create a social networking application. The components seem very comprensenvie, offer many different services including: Activities, Notificiations, Groups, Blogs, Files, and so on.
Elgg, started in 2004, is an open source social engine which powers all kinds of social environments - from education and business to martial arts and rugby. If you are looking for a professional social intranet or want to run a site for your organisation, Elgg is a great choice.
