StudyBlue offers a social networking approach to studying. You can create classes, add professors, join networks and share documents and class notes not only with your classmates but also with those from other colleges. Like all social networks, it requires that you bring your friends over or it wouldn’t be very helpful. However, it allows you to read the public notes of other members of the site and that might serve as a very useful feature even when you don’t have many of your friends joining the site.
Sign up for an account here: http://www.studyblue.com