...has to be The Skeptics Guide to the Universe.
Percy actually mentioned it on EvC years ago and I have been listening to it ever since. They often have heavy hitters in the science and skeptical community on as guests. I have hunted for good, entertaining science podcasts and SGU is never beat. They are funny, informative, and well produced.
If you like comedy and music mixed in with your science/skepticism, you should check out the Geologic podcast. Don't let the name fool you, it has nothing to do with geology. The guy who makes it is named George (Geo for short). He was the MC at TAM9, has a bunch of skeptical music that you can buy, and is a generally funny guy. While aspects of the show are more music nerd than science, it is generally a very entertaining podcast. It also has moments of being profoundly deep.
BUT if objects for gratitude and admiration are our desire, do they not present themselves every hour to our eyes? Do we not see a fair creation prepared to receive us the instant we are born --a world furnished to our hands, that cost us nothing? Is it we that light up the sun; that pour down the rain; and fill the earth with abundance? Whether we sleep or wake, the vast machinery of the universe still goes on. Are these things, and the blessings they indicate in future, nothing to, us? Can our gross feelings be excited by no other subjects than tragedy and suicide? Or is the gloomy pride of man become so intolerable, that nothing can flatter it but a sacrifice of the Creator? --Thomas Paine