open culture has a nice collection of recommended podcasts listed at their site. If you're a PBS/NPR kind of person, this list may hit the sweet spot for you. It ranges from daily Garrison Keillor stories to Scientific American's technology news to "Shakespeare-upon-iPod", a series of discussions on and readings from the bard himself. Clearly a lot of thought and effort has been put into compiling this list. If you're looking for something a little meatier than usual to listen to on your daily commute, you might find a gem here worth subscribing to.