Thanks to a link from BoingBoing, I saw Kiddie Records Weekly. That's just awesome! They're taking a bunch of old vinyl albums of kid's shows from the 1940s and 50s and releasing 1 each week for the entire year 2005 - free for download.
I'd found Gerald McBoingBoing a while back from another source, and it's one of Evan's favorite tracks on my iPod (after D-O-G Spells Dog, by Mel Blanc - I even get to perform that one sometimes). Really looking forward to getting all of these classic shows!
Now, if only they had an RSS feed with enclosures so I could automagically download every show when they're released, rather than having to remember to check once a week. I just know that I'm going to miss a couple...