It's hard to explain the basic human urge to pursue microwave cheese puffs, cold cuts and toaster waffles, but admit it: You love the stuff. Since Costco sells items like these in mega-quantities, it hires food demonstrators to hand out tastes, and you can count on snacking on at least ten selections any afternoon of the week at this giant discount warehouse. Whether stuffing your face with such freebies will stop you from making impulse purchases -- a new set of tires, say, or a big-screen TV -- we can't say. But at least you won't be light-headed from hunger when you throw down your credit card.