I've been listening to various podcasts and one that is less well-known that I particularly enjoy is "Point of Inquiry". There are some really great interviews with top scientists and intellectuals. For example, from watching science programs such as Nova, I'm a fan of Neil deGrasse Tyson and there are some great interviews where he shares his opinions on topics such as politics and education. Other notable interviews I've listened to are with Paul Kurtz, Carl Sagan, Richard Dawkins, and others. The interviewer, D. J. Grothe is also one of my favorite interviewers. There is a complete archive starting from Dec 2005 that I've slowly been listening to. Using iTunes as a podcatcher, there is an easy way to access the full archive via iTunes which is free.