This post seems to have gotten a lot of traffic from Google, so I'm going to keep updating it as I find more excellent podcasts. Leave your finds in the comments!
I am not the biggest fan of exercise, primarily because I find it boring (I climb stairs, go for walks, or use the elliptical or erg machines), and my boredom draws attention to the fact that exercise is less comfortable than sitting on the couch drinking wine and watching The Dog Whisperer. But I believe exercise is important, so I combat the boredom with podcasts. The following podcasts are so good, I go to the gym just to be able to completely focus on them.
"Real stories told live, without notes" - a simple concept, and absolutely compelling content. Dan Kennedy created this series, and each week a new episode is released with a 10 to 15 minute story that may be hilarious, touching, or simply jaw-dropping.Check out some sample episodes here. I strongly recommend Jon Levin's "Elevator ER." Among the more awe-inspiring stories is Deborah Kiley's "Lost at Sea." Seriously, every week is a surprise.
I've just discovered this one, and it's also awesome. WNYC's Radiolab is the first podcast I've listened to that has experimented with the medium - different music, sound effects, overlapping voices, and more. The content is awesome. Mostly science topics, but with history, anecdotes, and interviews tossed in. Episodes are typically an hour, which is a bit long, but they are really worth it. They've also produced some shorter episodes - so you can ease your way in.
This podcast comes out two or three times a month, is 10 to 15 minutes long, and usually features poetry reading plus some commentary. It's really brilliant, and I especially like the episodes that do a retrospective of one poet's work and the themes throughout (unfortunately this is typically an obituary episode...) The Poetry Foundation website is even cooler than the podcast itself, with a tremendous amount of poetry, biographies, analysis, multimedia, and on, and on. Look at this article on Ten Poems to Get You Through Science Class this Year - supercool!
Now, Girlfriend MD won't be for everyone, as she is explicit and some readers are likely to be squeamish. The premise of the podcast is that Dr Sanaz Majd answers women's health questions that you'd only ask your doctor if she were also one of your closest friends. Some great recent episodes provide info on getting rid of menstrual cramps, why women get migraines, and the differences between all available emergency contraception methods. Useful stuff brought to you by an expert! Dr Majd is trying to plug her cohost's book with the podcasts, but delivers a valuable service nonetheless.