The Warped Tour is a little slice of heaven for teenagers. Several dozen punk bands are crammed together for one long day, shredding eardrums with their sonic assault, and thousands of kids from all around metro Atlanta thrash and mosh and crowd-surf on an asphalt sea of litter, sweat, flesh, tattoos and black T-shirts. This is the spirit of rock 'n' roll, of instant gratification and anti-authoritarianism. And it's that very spirit that has the entire music business shaking in its Doc Martens. Because you're hard-pressed to find a kid at Warped who isn't downloading -- illegally, for free, sometimes...