I used to think YouTube was just a site where I could find stupid videos, but recently I discovered that it's actually a great place to find old, often-obscure songs.
Honestly. Just visit the site and type in the name of a song -- chances are someone posted a video or still image along with the song you're seeking.
For example, I heard a song by an artist named Sylvia on a 1970s-era episode of Soul Train this weekend. (Yes, I still watch Soul Train!) I liked the song, so I did a search on YouTube and found stuff like this:
Yeah it's cheesy. Sue me. Anyway, try it out see what you find for yourself.