Surprised this hasn't come up before. Or if it has, I completely missed it.
This being the season of things indoors..... I spend a lot of time on a stationary bike, so podcasts are a natural. Outdoors, distraction=disaster, so I keep my attention on my surroundings. Indoors, I can close my eyes, hammer... and listen.
I've enjoyed the "How Stuff Works" series, but at the moment I'm obsessing on:
Just as reassurance to you liberals, its politically neutral as far as I can tell. No Marxist or Limbaughesque revisionism.