academic earth: because everybody deserves a Harvard education. This site gives you access to lectures and courses from top universities around the globe- surfing youtube won't make you this smart.
pbs video: a great place to catch up on tons of educational pbs shows.
i tunes u: download free lectures, classes and educational information. Cheaper than Lady Gaga's new CD - and better for you too.
ted: the tagline says it all - ideas worth spreading, riveting talks by remarkable people, free to the world. My favorite is photos that made history.