Don't know much about geography? Physics? Nanotech? There are a number of really good video and audio resources available. Try the Research Channel, the Royal Society, Open Source Physics, everything you wanted to know about economics, the dismal science or it's cousin, political science... Then there is MIT World, Carnegie Mellon's open source learning initiative, Connexions, Vega, and the Princeton collection. Wikiuniversity is always interesting, Berkeley does a mean podcast, and the Edge video library is always, well, cutting edge. Stanford has the iTunes connection, and Fathom is a wide ranging site. Do you have a great resource? Share it in the comments section below.