The horror-themed web site The Monster Club has an excellent archive of old-school Halloween appropriate radio broadcasts.
The collection includes well-known classics, such as Welles' famous Mercury Theater War of the Worlds adaptation. However, there are some odd surprises mixed in. For example, there are several radio adaptations of then-popular suspense films. I've always known that radio plays were sometimes adapted into film, but I was unaware that this process cut both ways and was surprised to see how long these adaptations continued to be made. The Monster Club collection includes adaptations of The Day the Earth Stood Still, The Birds, The Wizard of Oz, and Gaslight, among others.
Even if you don't have time to listen to anything, the titles and show summaries for many of the lesser known broadcasts are worth the click through. Series include the The Price of Fear, Beyond Midnight, and the wonderful The Strange Dr. Weird. Here are a few choice episode summaries:
The Snowman Killing: A family with 2 boys moves into a new house. One boy begins to see a snowman no one else can see, while the other develops an odd malady.
Sub-basement: A mal-intending man takes his cheating wife to the sub basement of the department store where he works and discovers a horrible creature.
An Eye for an Eye: A chef creates a fantastic new dish, live octopus. Unfortunately, revenge is on the dessert menu. Starring and hosted by Vincent Price.
The collection also features performances from some of horror's most famous icons: including Peter Lorre, Boris Karloff, and, my favorite, Vincent Price.
Speaking of the price of fear, the whole darn collection is free. All treat, no trick. Happy Halloween.