I finally got on the podcast bandwagon a few months ago while I was holed up in my room doing renderings and what not for finals. A podcast is essentially internet radio except you download them like songs and, at least in my experience, they're free. My favorites thus far are:

99% invisible - city flags. They also have a Kickstarter right now.
Jay and Silent Bob Get Old Smodcast -  listen to 1-6.
The Nerdist - so far Bill Nye and Kevin Smith were both excellent.
Planet Money