A co-worker introduced me to Radiolab recently. It is a radio show that is also available as a free podcast. Each show discusses a specific topic from a scientific angle: why we sleep, how we remember things, even love! It is, without doubt, the best radio show that I have heard. Go get it now, get all the episodes. Buy a music player if you don't have one already, if only for Radiolab.
The hosts of RadioLab are Jad Abumrad and Robert Krulwich, and they do a wonderful job of interviewing people to bring out the joy of inquiry. Each show leaves me with a sense of wonder for the topic. In addition to the excellent production quality, Jad and Robert have a knack for finding the experts and asking insightful questions.
This might just be the second coming of radio. The Internet has allowed good content to find its audience. Without the Internet, a show like RadioLab would be confined to the few cities that broadcast it, and at very specific times. Now, a student in India can listen to Jad and Robert at whatever time is most convenient.