Donate them to your local library or school if the content is relevant. Some schools will also use cassette tape for crafts (there's a rumor that it makes great puppet hair).Try giving them away on Craigslist or Freecycle. You'd be surprised at how many people will jump at the chance to own a bit of music/media history.If you have an especially impressive collection, try selling them on eBay or Amazon.
added by Peter Schmidt to music room (3 months ago)
Been thinking of a way to use old tapes that I can't really part with. When the music studio room is built, not only will it not deflect sound it will look really cool as well!