I've been a fan of podcasts (or recorded audio/radio for those intimidated by the term) ever since I started picking foraminifera, a task which involves hours under the microscope. While music and audiobooks are always welcome companions, the sheer variety of podcasts have made it my go-to for laboratory work and commuting (apart from NPR).
Though I have come across many podcasts, I still don't think that the optimal way to search for podcasts of interest has been streamlined yet. This, on hindsight, might perhaps add to the lure of podcasts as they are things that you discover from a good source.
Here's a list of some of the extant podcasts that I'm listening to right now and would earnestly recommend. I've kept NPR-based podcasts out of this list. I would appreciate your thoughts on your favorites in the comments. Hover for details and click for links:
Note: If you're looking for a podcast app on an iPhone, I would highly recommend Overcast.