I haven't done it yet but I've seen the patterns for crocheting with cassette tapes. One of my readers asked what you could make using the tape so I did a search and found these, but use your imagination I'm sure there's a lot more that can be made with it.
Cassette Tape Evening Bag
Cassette Tape Barbie Halter Dress
And to use the empty cases (LOL)
Cassette Tape Wallet