The Man Who Would Buy Everything, Everywhere: A graphic designer in Sacramento copies the barcode on his Safeway card and passes cards around to people all over the country. (Link from Digital Daydreaming.)

My market, Hen House, issues what they call rewards cards--I get a discount on purchases, but I also get "rewards," i.e., when I buy a certain number of certain products, like salad bar salads or boutique breads, I get a free one. They keep track of it, as long as I use my card for the purchases, and when I've bought a dozen loaves of bread, the next one is free. And my receipt often contains coupons for items that I've purchased in the past.

At least I feel like I'm getting something for it. I really resent the stores that make you sign up for a card just to get lower prices. Rather than put things on sale, they sell their products for lower prices as long as you've told them who you are so they can keep track. I don't particularly care who knows that I buy a certain brand of soup or bread, or how many candy bars I buy. I do think that it's a symptom of a larger problem, though--the belief that your personal information is fair game to anyone who wants it.