This is the best: check out the iTunes Music Store (iTMS) and in the upper left hand nav box you'll see a link for iTunes U at the bottom. This takes you to the iTunes U central area where a dozen or so universities have started putting college courses, lectures, and other podcasts online for the public to download for free.
Psychology, business, technology, art history, quantum physics, social sciences, language, literature, stuff on how-to like teach and write - there's months and months worth of stuff to listen to and learn. Pretty cool!
Some of the universities are a little on the slim side as far as content goes. Stanford and Berkeley were my two favorite spots for downloads, having not only the most total but also the most in liberal arts and social studies, though there are some goodies in some other places (Seattle Pacific, which seems to be Christian, has some interesting stuff on the Lord of the Rings as a Defence of Western Civilization). Stanford has a few lectures by the Dali Lama in both the Philosophy and Spirituality sections. Berkeley had a neat section for the study of sex and sexuality in history.
And most of these are pretty hefty - many weighing in close to two hours apiece. I downloaded a whole bunch to pick through while I'm at work. I've got a lot of spare mental time on my hands doing thoughtless work and these are perfect for keeping my brain busy instead of drifting off into thoughts that can often lead in a depressing direction. ;)
Anyway, thought I'd spread the fun news. For those of you still in college this may be depressing news but for me, I miss the charge my brain would get after a good day's learning at school. ;)