* Astonishing Legends - Basically the "Unsolved Mysteries" of podcasts, and it's amaz... er, astonishing!
* The Eastern Border - Latvian Journalist's perspective on living in the baltic states in the soviet era
* The Dangerous History Podcast - An anarchist/libertarian college history professor's take on various historical events.
I found out about Astonishing Legends when I was reading up on Tamam Shud, and one podcast led to the other, which led to the other...
Astonishing Legends is both great and pretty universal. I think everybody should listen to it. The other two are great too, but probably appeal to more specific audiences. I will say, though, that if you're not particularly libertarian (I'm not), you might still give Dangerous History a chance. It's very good about calling out all the actors in any given event on what they've done, without slipping into a mythological "this was the good guy, this was the bad guy" simplified narrative.