U Illinois-Springfield and U San Francisco have developed ed-cast, billed as an "international clearinghouse for sharing lectures, conversations, speeches, and related podcasts for higher education." It's a bit anemic at the moment (I count only 41 "edcasts"), but that number is certain to grow with time.
I heartily recommend trying podcasts. Traffic in our area is horrendous; sitting in my car somehow feels far more productive when I can listen to a lecture. And audiobooks make long road trips far more enjoyable.
I've also found that students respond well to being offered a choice between reading and online multimedia for their homework assignments.
Thanks to ResearchBuzz for the tip.
Addendum: I don't know if it's a compatibility issue, but I can't seem to get search to work on their website. Instead, try clicking on the column headings under "results," which gives you a complete list, organized by that heading.