Here are three of my favorite podcasts.
Two of these are from Slate Magazine
I've been a big fan of the Political Gabfest for quite a while now. It's from the (moderate ) left, and is highly informative, fun and thought provoking.
Slate also has a Cultural Gabfest, which is also very interesting . These podcasts have many cool links to the topics being discussed. Slate also has a new Sports Gabfest, which I haven't heard yet.
The Political Gabfest: (posted on Fridays)
The Cultural Gabfest (posted on Wednesdays)
"Truckers, Shuckers, Freeks and Geeks", hosted by Mark Allen, used to be a weekly show, but now appears more irregularly. The shows focus on country and rockabilly music from the 50's, with a more general 50's and 60's show on occasion. My favorite shows are his oddball ones, including a two hour episode of Elvis tribute records, one of the strangest,and most difficult to listen to genres. but a great slice of Americana.