I've recently found myself getting tired of my music and listening to podcasts instead. They're great for long rides in the car by yourself.
I think I tend to lean more toward radio shows rather than podcasts (probably because they're more produced and edited). NPR's shows are great:
Sometimes their podcasts lack structure, but I also like the 5by5 tech podcasts put on my Dan Benjamin. (5by5.tv) I like:
Build & Analyze
Mac Power Users
Always looking for new podcasts. What are you listening to?