podcasts for a road trip

Does anyone have any good suggestions for podcasts? I'm going to drive from Santa Clara to Tucson, and then from Tucson to Maryland. So we're talking about five straight days in a car. Good podcasts would be nice.

I've been listening to The Future and You, Hardcore History, the Singularity Podcast, and Astronomy Cast... I've downloaded JapanesePod101, and some others. But what do you guys listen to? Better yet, what are some good serialized podcasts of books or old radio shows? Any suggestions?