Here's a place that looks like it links to lots of archives of Old Time Radio shows, mp3s of episodes of shows from way back, '30s, '40s, '50s.
Calf Killer Old Time Radio.
I have quite a few OTR shows, burnt on discs some years ago. I never listen to them, but I know they'd be good. I tend to drift. Some are not great quality, but some are very clear. There are thousands of episodes out there of detective stories, mystery stories, horror stories, and comedies that you may never have dreamt existed.
One of my favorites, back when I was listening to them, was a show called "Diary of Fate." And, hey, sure enough, there's a link off to a directory of this show's episodes. There's only 25-some episodes, identified by the name of the main character of that episode.
The premise of "Diary of Fate" is that Fate (that inexorable force behind everything) is personified, and reviewing a big book that has the life stories of various individuals. He has a slightly sinister, satisfied-about-it voice when he does these reviews. Each review is an episode of someone who did something terribly wrong. Perhaps it could've been avoided, perhaps they might not have gotten caught, "but for a little thing." Fate says that a lot, "It was a little thing." Such as a happenstance visit, a red light at an inopportune moment, a phone call that delays you, etc. And in the episodes it's these "little things" that Fate uses to seal their fate!
A common premise would be trying to get rich by killing someone in the way. But the little things pile up and next thing you know...their life's down the drain! It's a good show.
Calf Killer has lots of links, and some of these shows I recognize as ones I have. The "Adventures By Morse" link doesn't go anywhere live, and I only tested a couple links.
As far as I know, they're public domain, either that or they're so forgotten that no one cares.