I've exported my current podcast list and put it on my sharing page. I've only tested this once, but I believe you can save the podcast locally and then import it into iTunes. I don't know if it will replace the podcast you have or add to it, so I suggest exporting your list first. Caveat emptor.
What did me in? Well, the specialty casts on digital photography and security, and NerdTV (Cringely) are good, but what really got me was the BBC's Channel Four. In particular, their weekly show 'In our Time'.
Catherine the Great. Negative Numbers. Friendship, Human Evolution. The Oath. Where the heck do they come up with these shows? Do they pull them out of a hat?
The guests are always marvelous. They host invites two to three English Dons and lets them go at the topic, with a bit of guidance. It's a bit different from American talk radio. Instead of lunging at each other's throats they very politely contradict one another, but pretend nothing of the sort happened. They're not always smooth or even terribly articulate, but they are wonderful.
I get this podcast via iTunes. If you search you can find it, it's a bit hidden I think. The BBC also has a download list but I think the archives are shallow. (3/12: A contributor also suggests checking out the BBC's Listen Again page for more of an archival view.)
Here's a few notes on Catherine I picked up:
1. They are rather cute about Catherine's love life, which is generally the first thing people remember about her. In the US this would be the entire episode.
2. Vaccination (immunization) was in fashion. She was Protestant (german) and the catholic church opposed immunization as being "against the will of god" -- ie. unnatural. Catherine had her family immunized - a rebellious act. (Is this really true? I couldn't find any verification on the net. It's fascinating.)
3. She created a marvelous home for foundlings (orphans) in Moscow. No child survived there past the age of one year. (Is this true? Maybe it was the first few years?)
4. Russia in her time reminds me of a large US corporation. Not a democracy, but neither a classic aristocracy. More of a corporate oligarchy, but severance might have a sharp edge to it.