A couple of links I have in my bookmarks/favorites for old time radio programs:
http://www.oldtimeradiodownloads.com/index.php
http://www.dmoz.org/Arts/Radio/Formats/Old-Time_Radio/
Http://archive.org will give you the entire know library of known OTR recordings, all for free. All the podcasts and radio shows that play OTR get their collections from there. Its invaluable resource for classic media.