These are my regulars:
The Bugle
The Classic Tales Podcast (readings of classic books)
Dan Carlin’s Hardcore History
Common Sense with Dan Carlin (current U.S. politics)
Friday Night Comedy from BBC4 (I only listen to the News Quiz episodes)
New Yorker: Political Scene
NPR Wait, Wait…Don’t Tell Me
NPR: Intelligence Squared (Oxford style debates on a variety of topics)
NPR: It’s All Politics
The Root (from Slate, current events from an African-American perspective)
Slate Culture Gabfest
Slate Political Gabfest
Slate Hang Up and Listen (sports - I’m not really into sports, but it’s funny)
Slate’s The Afterword (reviews of non-fiction books)
Stuff You Should Know
Stuff You Missed in History Class
This American Life
Radiolab
I just want to put my vote in as someone who enjoys Marc Maron’s opening monologue.
The Pod F. Tompkast is a comedy podcast done by Paul F. Tompkins.
I just started listening to You Made it Weird by comedian Pete Holmes. It’s in a similar vein as WTF in that it’s a long conversation by two comedians but the hosts have different personalities.
The AV Club has a weekly feature called Podmass that reviews the best podcasts of the week that the AV Club listens to.
Every general subject podcast* I listen to has been mentioned so I mostly just wanted to pimp Harcore History some more.
I am torn between that the series on the fall of the Roman Republic and the Punic Wars series as my favorites. He is always apologizing for the long form shows, but they are without fail amazing. This recent one is fantastic so far (I am only 2 hours in).
*I also listen to some sports Podcasts, most of which I won’t recommend, but if you are into Baseball I can heartily recommend Up and In: The Baseball Prospectus Podcast and ESPN’s Baseball Today with Eric Karabell and (usually) Keith Law.