The Memory Palace: This is the way history should be taught, but rarely is. Nate DiMeo takes past events and puts you in the middle of them, in a way that makes you emphathise so much with people from the past. Each episode is a little short story, and they're often only a few minutes long. A great example is this description of when Niagra falls stopped. I have listened to the entire back archive, and want more. Only downside is it's a looong time between new episodes.

The Haskell Cast: Panel discussion with a guest, there is a lot of expertise amoung them and I'm often scrambling to keep up with the barrage of ideas. If this seems too tame, check out The Type Theory Podcast instead..

Benjamen Walker's Theory of Everything: Only caught 2 episodes so far, but they've both been great. Short, punchy, quirky, geeky. Astoundingly good production values.

Serial: You probably already know about this high profile TAL spinoff. If you didn't before: You're welcome. :) Nuff said.

Redecentralize: Interviews with creators of decentralized internet tools like Tahoe-LAFS, Ethereum, Media Goblin, TeleHash. I just wish it went into more depth on protocols and how they work.

Love and Radio: This American Life squared and on acid.

Debian & Stuff: My friend Asheesh and that guy I ate Thai food with once in Portland in a marvelously unfocused podcast that somehow connects everything up in the end. Only one episode so far; what are you guys waiting on? :P