Thought I might share what I listen to, and see what others listen to.
OMEGA TAU - Science & technology podcast, in English & German. Lots of space & aviation related topics, and highly recommended.
SKEPTICS GUIDE TO THE UNIVERSE - I'm sure everyone has heard of this.
SKEPTOID - Small 10 min eps dealing with a subject, sorting out fact from myth.
PROBABLY SCIENCE - Two stand-up comedians, both with a science background, have guests on and discuss science news. Very funny, very good.
THE DOLLOP - Two guys deal with an American history subject. Extremely funny as well as being slightly educational.
TOFOP / FOFOP - Australian comedian Wil Anderson and his actor mate Charlie Clausen prattle on about stuff, often involving Batman or time travel.
THE WEST WING WEEKLY - I loved the original series and this show reviews each episode, often getting the directors, actors, etc to give us insight into what went on.
WAIT, WAIT - DON'T TELL ME - An NPR news review comedy show. Obviously US-focused but very enjoyable.
SPACE ROCKET HISTORY - A surprisingly good podcast dealing with individual mission, spacecraft development, etc.
THE SPACE ABOVE US - Another surprisingly good podcast on the US manned space programme.
THE FIGHTER PILOT PODCAST - An ex-USN F/A-18 pilot takes us through various aspects of being an aviator: what you wear, what the weapons are, what the carrier landing signals mean, how they would intercept an aircraft, etc. Highly recommended.
SUPEREGO - PROFILES IN SELF-OBSESSION - How do I describe this? Incredibly funny (if you have a sense of humour like mine). They don't do the podcast anymore but the previous eps are available. My favourites are anything involving Cylon Jim and Cylon Phil. Especially if they are going to hit the karaoke bars.