i-Tunes U (U-tunes) on i-Tunes fucking kicks ass! Especially since it is free (for now)… I found that listening to them on long road trips is very enjoyable, just like listening to book on tape. Now, I suppose much of the visual part of the lecture is lost, but I still found the topics I chose (most dealing with either the social sciences or natural sciences, but a few on literary topics) quite informative and interesting.

-sib