What would you do with a box full of records that were meant to only be played once at a radio station, as demos of new songs from the 60's & 70's? After played once. They were never be played again, but thrown away. Some of these songs became top hits..

Have them appraised.

Certainly they have value. Looks like others have already talked here of getting an appraisal .. and given a few suggestions re: selling them (to a collector, via ebay, etc) Another way to go (if you're not looking to make a ton of immediate cash) .. might be to donate them (or I guess you could try to sell them>) .. to a musical archive or museum. These are more than just music. They are a part of that industry's history. So they are artifacts as well as records. You could write off the donation on your taxes if you went that way (in US). Not sure in other countries how that works. As for which institution or repository? Depends on what kind of songs you're talking about. Rock 'n Roll Hall of Fame? Country Music Hall of Fame? Smithsonian? On the other hand, could just sell them on Craigslist! lol

Check for damage first even the slightest scratch will de-value them, the pristine ones I would try selling to a collector, the rest I would put on ebay.

one word - EBAY

Demos or DJ only records can be worth some money(go to local bookstore and look for a book like Goldmine records price guide. They might even have a website). They're not necessarily the bible of record prices, but it could give you a hint of their value. If it were me however, I'd keep them and add them to my ever growing collection of music.

They're quite likely very valuable. I'd take 'em to someplace (Antiques Roadshow comes to mind) that could see what you had and give you an estimate of their value. Sounds like a treasure trove you have there! Good luck! :)

Auction the popular ones and give the money to charity. The rest (and radio stations get a lot of junk, folks)...skeet.