Microsoft put up Richard Feynman's Messenger series of lectures, which were on physics at Cornell.
http://research.microsoft.com/apps/tool ... index.html
For anyone who isn't familiar with Feynman, he was one of the greatest physicists of the 20th century and won the Nobel prize for his work on quantum electrodynamics. He worked on the Manhattan Project when he was fresh out of graduate school (I believe; he was very young at the time), and is arguably more famous for his personality and the books he wrote about his life, which contain tons of short stories that are hilarious, insightful, and contain things people wouldn't expect a scientist of his caliber to do (drugs, living with vegas showgirls, etc). He had a lifelong distrust of authority and was really one of the most interesting personalities of the 20th century. He is also very famous for the lectures he gave.
If you want a light, fun read pick up one of his books (NOT one of the physics one). "Surely you're joking, Mr. Feynman" would be a good place to start.
He was one of my biggest inspirations when I was an undergraduate and was unsure if I wanted to continue in a technical field.