Web site Academic Earth is like Hulu for academic lectures, pulling free lectures from Berkeley, Harvard, MIT, Princeton, Stanford, and Yale into one attractive, easy to navigate site. It's incredible (albeit completely US-centric in terms of the universities selected). The site clearly takes its cues from Hulu and iTunes on its design, but it's ten times better than either, because it's open. The videos can be embedded anywhere or downloaded and enjoyed wherever you want to take them. It's easy to use, has tons of great content, and it doesn't cost a cent.