(FORTUNE Magazine) – It wasn't until after the fourth straight day of FedEx deliveries that I peeked at the packages my roommate was receiving. He lifted their contents like they were big-game trophies--giant bottles of vitamins, a box with four-dozen razors, bath kits, coffee cans of weight-gaining powders--and I understood how the medicine cabinet had suddenly been overrun. His total on the last order, for example, was $0.98, including shipping, the result of his creative use of coupons from the e-pharmacy PlanetRx.com. He had previously parlayed a few first-time-customer coupons into a free order. Then, for referring his friends and relatives, PlanetRx had rewarded him by passing along more coupons--hundreds of dollars' worth--which financed the package in front of me. Arriving next week were smoke detectors from OurHouse.com, cat food from Petsmart.com, and A Bug's Life on DVD from FamilyWonder.com. Total price at retail: $208.80. His cost: $29.81.

Auctions and naming-your-own-price may have just whetted the appetite of fevered online bargain hunters. Now they can troll Websites dedicated to finding online coupons (which consist generally of codes that earn discounts when entered into sales orders for the appropriate e-tailers). My roommate found his coupons on Pricezilla.com and Dealitup.com. But those are just two of a host of sites that have handed Web shoppers even more power to pick and choose among e-commerce sites desperate for visitors--so much so that they're willing to give away their stuff.

Some of the coupon sites are simple bulletin boards, while others like Dealitup.com or Dotdeal.com (both of which attempt to profit by selling ads) post the deals uncovered by their users, making sure no deal goes unnoticed and no coupon unredeemed. "In the real world, we see about 1% to 2% redemptions," says Dotdeal.com's Vikas Luthra, a former brand manager for Procter & Gamble. "Our numbers have been as high as 90%."

With the massive reach of the Internet, the sites provide a universe of coupons infinitely larger than any shopper would get in, say, a local paper. And that massive reach also raises the potential for abuse. Consider Value America, the now troubled online retailer, which offered mammoth $100 discounts to first-time customers. That wasn't enough for some, who exploited a loophole allowing them to set up multiple accounts--each of which came with the $100 discount. "I had 38 personal accounts," says Dealitup.com co-founder Robert Khoo, who runs his site when he's not attending classes as an undergraduate at the University of Washington. "I took no steps to hide it either. They all said 'Robert Khoo' and they all had the same address." Khoo used the coupons to bankroll an orgy of Christmas presents. Adds Khoo: "I even received an angry call from one of the VPs" at Value America. (A Value America spokesperson did not return calls seeking comment.)

For now, most e-commerce sites seem willing to put up with the potential abuse (they've also gotten savvier, trying to short-circuit overuse by making coupons valid for only a few hours). E-tailers see coupons as valuable word-of-mouth advertising. Greg Drew, CEO of electronics site 800.com, whose 1998 three-for-one DVD coupon is widely believed to be the deal that started it all, has no regrets. "When we launched the promotion, we had 100,000 new customers in 13 days," says Drew. "Even more pleasing, more than 50% of our revenue this year came from repeat customers."

All of which is fine with my roommate, who is well stocked with toiletries for the immediate future and is building a library of pricey DVDs basically for free. He'll remain a loyal customer--as long as they're handing out the coupons.