Whenever I have to drive, I make sure I have my iPod with me. While NPR is my only radio station, its programming is not always what I want to hear at the time. With that in mind, and going back to my childhood listening to CBS Radio Mystery Theater (back when AM radio was used for more than talk radio), I now listen to the best radio show around.
Robert Krulwich and Jad Abumrad are the hosts of each show, and they create a movie for the ears. In the words of the website, "Radiolab is a show about curiosity. Each episode is an investigation - a patchwork of people, sounds, stories all centered around one big idea." This means that topics will likely include psychological topics--memory, curiosity, deception, music, the brain, nostalgia, tickling, coincidence, morality, science, parasites (and effects on behavior). Every episode is seemingly a wonderful interdisciplinary show that feeds the mind.
One recent show was about the Obama Effect. The show was about people's perceptions related to their scores on intelligence tests (or some other term that was used). Results included differences in test scores when minorities had different beliefs about what the test was about. It really challenged the notion of the efficacy of intelligence tests.
In short, it is my favorite radio show and I highly recommend it. Please try one episode and you'll see. Enjoy!