Using the iPhone's Podcast app, I'm able to listen to thousands of podcasts in the car. It's priceless (and free), and a way to soak up knowledge I otherwise wouldn't have time for.
Some of my favorite podcasts are (links open iTunes):
And the best part is that because the iPhone can play podcasts at 2x speed, and since "60 Minutes" is really just 42 minutes without the ads, that means at 2x I can listen to a full 60 Minutes show in just 30 minutes (interestingly, "2x" is actually 1.5x... I guess 2x sounded better to Apple). Amazing.