The revolution started with spandex and mixtapes. Exercise helped people fit into stone-washed jeans. Listening to Air Supply was pretty sweet. Music and exercise forged a symbiotic relationship -- it was a win-win. Soon after, Walkmans conquered the audio universe, and later, radio tuners appeared on athletes' biceps. Now, iPods and MP3 players outnumber treadmills.

iPod Lets You Download a Personal Trainer