If you've ever been to a roller derby match, you've probably wondered where the girls found all that stuff they wear: the skull-adorned knee socks and ruffled panties and tutus and booty shorts emblazoned with "Sk8 or Die." In Denver, where derby thrives with two competitive teams and a healthy following, the athletes now have the luxury of their own roller derby boutique, Derbyville, which opened about a year ago along Broadway's antique row, thanks to enterprising Rocky Mountain Rollergirl Amy Harrold, aka Pretty But Ruthless. But you sure as heck won't be shopping for antiques at Derbyville, which in addition to the aforementioned items also sells everything a roller girl could possibly need, from the skates and pads on up, as well as bout tickets and fan memorabilia.