"The Shadow" - Love that show, from the original Orson Welles voice(only one year from 37 to 38) to Bill Johnstone to Bret Morrison (I think he had the longest run)
ZenG: Speaking of the ad-lib sound effects. The echo-effect when they did the "Who know what evil lurks in the heart of men" was achieved by holding an empty drinking glass next to his mouth.
Love the "Dragnet" radio show as well.
It's fun to noticed when "Standards and Practices" kicked in on the Shadow. Like the 30's to the mid 40's, he didn't really have a problem killing the bad guy. Then only the bad guys killed people, then in the 50's the bad guy would come up with a plot the would kill people, but was always stopped before it could be implemented.
And the changes in law enforcement on Dragnet (ie no miranda rights, etc. )
EDIT: How could I have forgotten to mention "Edgar Bergen and Charlie McCarthy".. Bergen had such talent and good timing, he could honestly make you believe it was two different people talking. And to think people actually think Jeff Dunham is good..
Bergen could even cover mistakes and make that it to something great. I had an album with them doing a live bit reading (Twas the Night Before Christmas. Candice Bergen was on it as well and she was about 7 if that helps date it for you.)
He had done this bit on the radio before, that's how I knew it was an unplanned thing. He basically did something that was supposed to be a Charlie McCarthy line as himself. Doesn't change facial expression at all and just has McCarthy turn to him and say "That was *my* line Bergen."
The audience just died. I wish I could find it, it was done so naturally.. I really can't do it justice.