Chocolate lovers clamored for smaller portions. And in April, 2001, Masterfoods responded, tweaking its manufacturing to produce eight-ounce and five-pound customized bags and selling them online. Although these cost nearly three times the price of regular M&M's, they've become a growing niche business, with sales doubling every year, say execs. "We're using technology to give consumers the products they're after," says Bill Simmons, general manager of the Masterfoods business development team.

From colored bits of candy to hockey sticks and complex plastics, lots of items are now being tailored to individual desires. This is part of a continuing industrial evolution--from mass production to mass customization. The result is the mass market of one. And the Web is helping to bring it about. Companies are wooing shoppers with a digital version of the classic Burger King come-on: "Have it your way."