These are all light(ish) podcasts - they explain some things and they're very entertaining, but they don't get into the really hard-core aspects of their particular fields. You will not hear the actual math equations, for example.

*Planet Money - economics - http://www.npr.org/rss/podcast/podcast_detail.php?siteId=94411890

*Radio Lab - general science - http://www.radiolab.org/series/podcasts/

*The Skeptics Guide To The Universe - skepticism + misc science/atheism/rationality - http://www.theskepticsguide.org/

And obviously I can't not mention my own podcast, translating Eliezer's Methods of Rationality fic into audio format:

*Harry Potter and the Methods of Rationality - pure awesomeness - http://itunes.apple.com/us/podcast/harry-potter-methods-rationality/id431784580?ign-mpt=uo%3D4

If you're interested in how your body works, I recommend Gerald Cizadlo's lectures. They are biology classes for nursing students at an American religious college. Because of his pathophysiology and physiology podcasts, I'm now able to explain the way nerves transmit signals (for example).

(Edited; I originally called nerves insane.)

The Australian Broadcasting Corporation has quite a few good ones. I like All in the Mind and The Philosopher's Zone http://abc.com.au/

Also, EconTalk, for economics. Their series on Adam Smith's Theory of Moral Sentiments is good, but intense to start with. http://econtalk.org/

Big Ideas has some great stuff. (And some not so great - be picky.)

• Econtalk

• HP:MOR

• http://www.rationallyspeakingpodcast.org/archive/

• If you ever watched/enjoyed BSG, the podcast is lots of fun - http://itunes.apple.com/us/podcast/battlestar-galactica/id73329453

• Audible.com - lots of stuff, there are many books you don't have to concentrate on too hard

Downvoted for bad grammar but:

Podcasts only go so far. I recommend downloading lectures etc. from youtube and converting to mp3. The best downloader-converter I've found for Windows is this, and for Linux, this (read the comments for how to get it to work). I assume you know how to find stuff on youtube so I'll skip the recommendations, but I've probably listened to thousands of hours of stuff from there and haven't run out yet.