One of my favorite podcasts is In Our Time, a BBC radio show hosted by Melvyn Bragg. Every week he gets some Brit academics into the studio to talk about something like Boethius or the Sturm and Drang movement. Bragg is good at asking productive questions and keeping his guests from getting stuck on some obsessive academic point. I listen to it almost every week.
For quite some time, BBC Radio 4 has posted the most recent radio programme. They got busy over the summer, and have now posted all of their old shows for download, dating back to 1999. They classify their shows by history, philosophy, culture, religion, and science.
If you're a civ nerd, it's great fun. Check it out.