As I drive the 30 minutes to work each day I listen to a lot of podcasts. Here are some of my favorites:
The History of Rome by Mike Duncan and his Revolution series
Dan Carlin finally someone who I can agree with, mostly.
The History of Byzantium A great overview of the forgotten half of the Roman Empire
Freakanomics - fun stories about economics and human nature
Hanselminutes - Amazing author and speaker on software development with Microsoft slant
The Norman Centuries - Forgotten history of the Normans
Planet Money - great stories on economics
Security Now by Steve Gibson - essential security news
EconTalk with Russ Roberts - great guests and Austrian economics.