Social Bookmarking for Academics

CiteULike is a free online 'social bookmarking' tool aimed at promoting and developing the sharing of references amongst researchers. In the same way that it is possible to catalogue web pages (with, researchers can share information on academic papers with specific tools developed for that purpose. CiteULike say they have around 2,000 peer-reviewed papers posted on it every day. 

A quick search for the broad term 'medieval' brought these results.

There are also 'groups' - collections of users creating shared libraries of links. They are useful for keeping track of a particular topic or what everyone else in a lab, class or academic department is reading. You can start your own groups and join existing groups. A quick search for 'history' revealed the following 'Groups interested in history': 
  • DigitalHistory
  • C17 Politics Literature Culture Thought
  • 18th-century history culture and society
I'd be very interested in your comments as to the site's usefulness using your own more specific search terms or groups...