These are enjoyable enough that I did some searching and found podcasts of some of the old radio shows that I've just added to my list:
- Cases of Sherlock Holmes
- X Minus One - a classic 50s science fiction series. A million could be years on a thousand maybe worlds...
- Old Time Radio Scifi - may be easier just to search for this in iTunes, as they don't have an obvious iTunes link.
- The Shadow - What evil lurks in the hearts of men? The Shadow knows...
If you come across some classic old radio shows, I'd love to hear about them...
'Suspense' is one of my favorite shows and 'X Minus One' is supposed to be a good sci-fi show, though I haven't actually heard any episodes yet. I've no idea if any of those are available as podcasts though.
*EDIT* Oops. I see X-1 is already on your list :P