From vinyl 78s and 8-tracks to cassette tapes, CDs and now MP3s, every new decade seems to bring in a new music format. Seeing as those cassette tapes are just sitting on your shelf collecting dust, you may want to clear some space by recycling them. Luckily, there are a variety of new and productive ways to use those old cassettes.
Call your local recycling program and inquire if they accept cassette tapes. While many do, certain places do not have the ability to recycle them. If they don't, they may be able to help you locate a program that does. You can also use a nationwide service like EMS Europe (see Resources), which recycles tapes free of charge as long as you cover postage costs.
Donate them. Goodwill and other services accept donations of cassette tapes that they then sell and use the proceeds to provide services for the needy. Before bringing them a large box of cassette tapes, however, make sure to call and verify that they can accept them.
Trade them. If you cannot sell them at a garage sale or give them away to friends, services such as Freecycle (see Resources) give users the ability to trade items to other people and groups around the world who are looking for such things. All it costs you is postage to send the tapes and cases.
Create art projects out of them. Cassette tapes have a nice retro feel to them now, allowing them to be turned into hip crafts. The magnetic tape from a cassette tape can also be unwound and used to tie things, like flowers in a pot. People have also turned the plastic cases into cheap belt buckles.