Five to Four : "a podcast about how much the Supreme Court sucks" with Peter from If Books Could Kill which got quite a few mentions
Embedded.fm : best tech podcast I know, nominally about embedded programming, but also a lot of peripheral topics, origami comes to mind. Few tech podcasts manage to discuss deeply technical issues in an interesting manner.
Conversations with Tyler: general interest podcast with long conversations with a diverse cast of sometimes very high profile guests. Just came across it a couple of days ago and was surprised I never heard of it. Tyler has had folks like Daniel Kahnemann, Noam Chomsky, Neil Stephenson but also has great lesser known people. A recent podcast was about the history of Chinese cuisine...
Just curious: how do you feel about post Had&Robert Radiolab?