The University of California at Berkeley at has made available a good chunk of its Fall 2011 courses via iTunes U for free! You can download courses on Biology, Chemistry, Economics, History, International Relations, Mathematics, Public Health, and more. These courses are entirely free – they require only a PC or a Mac with Apple’s iTunes software installed (also a free program). If you have an iPod, you can also take them on the go!
To look at the course offerings, click on this iTunes U link.