I'm currently taking their class on Machine Learning and I really like the way the Coursera classes are organized and presented.
For anyone who hasn't heard of them, Coursera offers free online courses which, unlike some other online courses with questionable integrity or benefits, are taught by professors from Universities like Stanford, Princeton, Berkeley, and the University of Pennsylvania. New lectures are posted every week and there are graded homework assignments with deadlines. Each course also has a message board that everyone can use to ask and answer questions. Since the structure keeps everyone at roughly the same place, the whole thing feels like a real class, but without the pressure of the "necessary evils" of education, exams and GPAs.
It's still a relatively new service, but someone back there must be happy enough with it because they keep adding new courses. I'll be interested to see what happens when more universities start offering more involved free courses, instead of just posting lectures on youtube (which is still pretty awesome btw).