(1) Old Time Radio Mystery Mondays - I just discovered this one today and it was love at first listen. I listened to a Hercule Poirot story and a very interesting episode about a man who kills his wife called "You Can Die Again." I love these old radio shows. The acting is awesome and over the top and both episodes were thrilling. I could listen to those stories all day long.
(2) Undisclosed: The State vs. Adnan Syed - This is a follow up to Serial. It's a little rough because the hosts are three attorneys rather than seasoned radio journalists adept at podcasts. Nevertheless, I am hooked. So far they have gone through Adnan's day, Hae's day, and Jay's day and they are thorough. They explore a lot of wholes in the story that Serial never bothered to cover. Seat T even wrote into them with a question about why they couldn't verify whether Adnan had an alibi by checking his email records since that's what he was doing at the library. I thought that was such a good question.
(3) Stacking Benjamins - I got turned onto this podcast because Paula Pant from the Afford Anything blog is a regular guest. These guys cover interesting personal finance topics and have pretty good discussions with guests. I really liked a recent episode in particular where the host interviewed a blogger from New York City who is having her wedding for $5000 or less. (She's only having like 30 people and it's on a Tuesday.)
(4) Radiolab - I've only listened to a couple of these but the stories were compelling.