Oh, way too many. Here's all the ones in my Downcast, most of which I stay current with or am working my way through backlogs of:
* Affirmation Nation with Bob Ducca (still in there in the vain hope that it will return one day)
* Analyze Phish (/Fish)
* All Songs Considered
* Call Chelsea Peretti – mostly just Chelsea Peretti being silly. Not essential, but fun.
* Comedy Bang Bang
* The Dana Gould Hour - comedians talking about stuff. Not essential, except for the one where Monika Scott talks about her experience being in a mass shooting, which holy shit.
* DecodeDC
* Doug Loves Movies
* Eban Schletter's Fantastical Musicorium
* Extra Hot Great, obviously
* Fresh Air - yeah, I actually listen to every episode, though I'm a month or two behind right now.
* Mike Detective (defunct)
* The Moth – those of you who live in/near non-tiny cities should check if they do their "story slams" nearby, in person. They're great fun.
* My Brother, My Brother And Me - delightful.
* Nerd Poker - Brian Posehn and some other comedians / writers play DnD. Pretty fun, though if you don't/haven't played yourself I don't know how accessible it is.
* On the Media - my favorite news-type show. Some interesting internet-related content too, on their new subpodcast TLDR.
* Planet Money - also a great newsy show.
* Pod F Tompkast (probably defunct)
* Pop Culture Happy Hour – seems like y'all mostly know about this already, but any EHG fans should definitely be listening to this....
* Radiolab
* This American Life
* Thrilling Adventure Hour - delightful old-timey radio stories that are really funny.
* The Todd Glass Show - it's rambly, really long, and his "special episodes" are mostly intolerable, but the sheer joy that Todd and his friends have doing silly bits is infectious.
* The Truth - "serious" radio fiction, like short stories or whatever but less pretentious. I'm a big fan.
* Welcome to Night Vale