Here's a vision of the not-so-distant future: Microchips with antennas will be embedded in virtually everything you buy, wear, drive and read, allowing retailers and law enforcement to track consumer items -- and, by extension, consumers -- wherever they go, from a distance. A seamless, global network of electronic sniffers" will scan radio tags in myriad public settings, identifying people and their tastes instantly so that customized ads, "live spam," may be beamed at them. In "Smart Homes," sensors built into walls, floors and appliances will inventory possessions, record eating habits, monitor medicine cabinets -- all the while, silently reporting data to marketers eager for a peek into the occupants' private lives. Science fiction? In truth, much of the radio frequency identification [RFID] technology that enables objects and people to be tagged and tracked wirelessly already exists -- and new and potentially intrusive uses of it are being patented, perfected and deployed. Some of the world's largest corporations are vested in the success of RFID technology, which couples highly miniaturized computers with radio antennas to broadcast information about sales and buyers to company databases. Already, microchips are turning up in some computer printers, car keys and tires, on shampoo bottles and department store clothing tags. They're also in library books and "contactless" payment cards. With tags in so many objects, relaying information to databases that can be linked to credit and bank cards, almost no aspect of life may soon be safe from the prying eyes of corporations and governments, says Mark Rasch, former head of the computer-crime unit of the U.S. Justice Department.