This is unbelieveable.
Courtesy of Kirk Demarais' excellent Secret Fun Blog you can download for free over 100 pieces of excellent mid-century and mid-century-ish music used in the Ren & Stimpy cartoons.
It's a brilliant collection and even comes with specially designed cover.
I chose to use the Sendspace download (see link on the blog page) to get them all in one big zip file. Enjoy!