Feynman & Silverlight: A great combination
Over at Microsoft research, they have put up numerous lectures from that great theoretical physicist and bongo player, Richard Feynman.
That little extra is achieved through the Silverlight app in which the lectures run: You get a timeline that makes jumping to different passages easy, it allows you to add your own notes at certain points in time of the video and you get extras like links to other stuff as well as a transcript running underneath.
Showing off of Silverlight features + lectures of one of the best physicists of the last century: Thumbs up!