Paul Graham on Start-ups, Innovation, and Creativity http://www.econtalk.org/archives/_featuring/paul_graham/
Paul Buchheit on Google, Friendfeed, and Start-ups http://www.econtalk.org/archives/2009/09/buchheit_on_goo.htm...
Looking over the archive, here are some from the archive that I liked:
Blakley on Fashion and Intellectual Property
Okrent on Prohibition and His Book, Last Call
Romer on Charter Cities
Boettke on Elinor Ostrom, Vincent Ostrom, and the Bloomington School
Hitchens on Orwell
Kling on Freddie and Fannie and the Recent History of the U.S. Housing Market
Karol Boudreaux on Wildlife, Property, and Poverty in Africa
Chris Anderson on Free
Taleb on Black Swans
In any case, I third the recommendation. The host Russ Roberts has a gift for explaining things clearly, and, rarer and more wonderful still, the ability to disagree and remain civil.