Here's a good article on the cassette tape, which is now 40 years old. When I was a teen, the tape was the only music format. Records were still around, but kind of fading. CDs were yet to make their mark. The tape was king. I had everything on tape.
Which, of course, means I've had to re-buy my collections on CD. But I haven't given up on the cassette. I have a cassette player in my car and I tape all my CDs for it. I occasionally go to record stores and thumb through the bargain bins full of old tapes. It gives me the chance to pick up something without risking $15.
I don't make mix tapes enough. I love the mix tape, but I rarely make the time to do it. Occasionally, a friend will ask for a mix and I'll have a ball coming up with one. Here's a good site on the Art of the Mix.
I just watched "Royal Tenenbaums" again the other night and that always gets me thinking about mix tapes. The soundtrack of both that film and "Rushmore" are such eclectic mixes, yet it all hangs together. Both those films and Quentin Tarantino's films inspire me to think about mix tapes.