'History That Doesn't Suck' by Prof. Greg Jackson. It is a history of the U.S., told in a flowing narrative type format that's easy to listen to. I like it because it counteracts my biggest peeve in the presentation of history where it is taught as discreet chunks that are seemingly disconnected. In this podcast, it follows the flow of historical figures and events as they naturally lead to new things rather than talking about each section in a vacuum.
'HP Lovecraft Literary Podcast'/'Strange Studies of Strange Stories'. A podcast with two hosts and normally a guest reader. The hosts talk about the relevant real life history of the story, as well as talking about the story itself, edited in between a reading of some or all of the story (depending on story length). It gives a good overview of the works and is tightly edited so that the host banter never rambles off topic. The podcast changed names when they ran out of HPL stories and fully branched out into other authors.
Update: A G3 just caught my eye and that's essentially an MP5.