I was looking around iTunes U for free educational videos to put on my iPod to support my space/astronomy outreach work. I found some great space stuff, but I also noticed some other (temporarily) free stuff. The PBS program The American Experience has been running a series of in-depth biographical films on U.S. presidents called, logically enough, The Presidents. They have made six of the complete films available as free downloads on iTunes U through Inauguration Day.
The six available subjects are FDR, Truman, LBJ, Nixon, Carter, and Reagan. I downloaded all of them to my portable hard drive for eventual viewing on my PC and/or iPod. I've been watching part 1 of the FDR show and it's excellent. You can also watch the full programs online at program's web site (including one on George H.W. Bush that is not available at iTunes U).