I'm a big fan of Podcasts. I listen to my favorite radio shows via podcast. I listen to history programs put out by the Smithsonian and other more academic affairs via Podcast. Needless to say this is right up my alley - Prof Brad DeLong of the Cal-Berkeley economics department has released Podcasts and notes to every lecture in his Econ 113 "American Economic History" course this fall.
The lectures are all titled very clearly, pick out a few that look interesting and give them a listen.