Here is a very charming history podcast. It is of the short monologue style, but it inserts audio fragments and by that makes optimal use of the podcast medium. Historicast. (feed)
With particular appreciation I listened to the episode about the Hindenburg disaster. The added value of the audio fragment is that it is authentic, in addition to it being very famous and dramatic. Here we see an amateur podcaster showing the way for podcasts to go, where mostly professionals still haven't gone. In my opinion, this is a podcast that is here to stay.