Physics works! The human pendulum demonstration.

Here's another one for the "The Web Is a Wonderful Thing" file: an eccentric physics professor at MIT has become an internet star via iTunes U. His enthusiastic and creative in class demonstrations (see pendulum demo above) are a natural crossover to the online world. So, if you've got a little free time, check out Prof. Lewin's physics lectures and expand your mind.

On a more related note, there are all kinds of lectures available on iTunes U for free, including a lecture series entitled City Visions: Past and Future from MIT's Urban Studies and Planning department.