I spent some time this morning looking over the Podcast directory at Apple. Hadn't been there in a while and was impressed with the the amount and variety of what is being produced. Below are two that I spent some time exploring and found to be interesting.
CHEM 1000 Class Demos Vodcast
Dr. Bob Burk of Carleton University makes available video of lectures and classroom experiments via iTunes. Available for download to your iPod or PSP. His classroom is set up with overhead cameras, similar to what you see on a cooking show, so you can look down on his experiments. Looks like he does a few quick edits and then makes them available via the web.