Here is an interesting link I came across while searching for the Feynman lectures -- Project Tuva.

http://research.microsoft.com/apps/tools/tuva/

It provides each of Prof. Feynman's seven lectures delivered at Cornell as a part of the Messenger lecture series. This format of posting lectures by Microsoft is absolutely amazing. I hope more such lectures especially videos of keynote lectures in leading conferences and congresses can be made available online.

-Arun