I'm loving Serial, I listened to nearly all of it today. Occasionally I listen to Startups For the Rest of Us (http://www.startupsfortherestofus.com/) but it's hit and miss if the content is relevant for me. Hardcore History is excellent.
It'd be nice to discover some more.
You'd probably like "Criminal" which is short crime-related stories. Only a few have been produced, but they've been picked up by the Radiotopia folks to do more and more often.
"WTF with Marc Maron" has some amazing interviews with people from the comedy and music worlds, along with short monologues from Marc's twisted mind. The (pay-for) archives are where the best episodes are (Judd Apatow, Louis CK, Ira Glass, Ken Jeong, Ed Helms, Dick Van Dyke, Mel Brooks, Dave Foley, Dave Grohl, Aubrey Plaza, Bryan Cranston, the list is endless) but the most recent 50 are always free. His interview of Robin Williams was incredible, and he just reposted it in the free stream recently.
Also on my playlist: 99% Invisible (stories about the design of things (more interesting than that sounds)), Good Job Brain! (pubquiz-themed trivia show), Ask Me Another (live trivia show), The Memory Palace (extremely rare, but fantastically interesting episodes), Born Yesterday (interesting tidbits from history), The Bugle (John Oliver riffs with a comic colleague from England), StartUp (Alex Blumberg recounts starting his own podcasting company after leaving This American Life), and of course This American Life and Radiolab (if you can stand the style).
Also, check out the big list of podcasts the new label Wolfpop just put out. Lots of good pop-culture stuff: Nate Corddry Reading Aloud, Denzel Washington is the Greatest Actor of All Time Period, The Canon (histrionic arguments about movies), and Maltin on Movies (calm discussions about movies) are the ones I'm trying at the moment.
Podcasts my family enjoys but I've had to cut mainly just for time: Planet Money (NPR/TAL-style explainers about the economy) and the Sporkful (good-natured arguments about the minutiae of various foods).
NPR has a ton of great, well-produced podcasts and radio-shows-made-into-podcasts: Pop Culture Happy Hour, Dinner Party Download, Wait Wait Don't Tell Me, Fresh Air.
Hope that gives you a good starting point.
EDIT: some other podcasts I've listened to but given up for various reasons, but which are definitely worth checking out: The Moth, RISK, Snap Judgment, On Being, Life of the Law (I think).
* Radiolab
* Stuff You Should Know
* Studio 360
But - Serial is definitely my favourite podcast of all time. I'm not sure there's anything better out there.
Radiolab is really an experimental way of doing audio. Jad is a composer and they break all the traditional rules to make it very immersive. Personally, I like it. But, I also like the virtually no production, talk podcasts too.
This American Life bookmarklet:
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* Hardcore History with Dan Carlin - only 2-3 episodes per year, but all very long and well-researched. Very entertaining.
* Planet Money - quick, short episodes of interesting money/economics/markets-related things.
* The Lowe Post - if you like basketball. Zach Lowe, from Grantland, interviews various people if note related to the NBA.
I really like Spider-Man: I really like the Amazing Spider-Talk podcast.
I like Dave Ramsay: I really like The Dave Ramsay Show (okay, it's just an hour of his daily radio show, but hey, it's also a podcast if I can listen on demand on my iPhone.)
I've come to be interested in the hobby of buying and restoring (and occasionally playing) classic (80s, usually) arcade games: I really like the Arcade Outsiders podcast.
I'm sometimes into World of Warcraft, sometimes into League of Legends, and I have Podcasts for both those games I'll dive in and out of.
I like to write and think about stories, as well as watch movies: I really like the Scriptnotes podcast. I enjoy the candor and outside-my-tribe perspective that Penn Jillette has: I really like Penn's Sunday School.
(Podcasts are a great way to dip your toes outside your tribe, a habit I highly suggest everyone try to develop.)