bar code

"You swipe the license, and all of a sudden someone's whole life as we know it pops up in front of you," said Paul Barclay, the bar's owner.

Mr. Barclay bought the machine to keep out underage drinkers who use fake ID's. But he soon found that he could build a database of personal information, providing an intimate perspective on his clientele that can be useful in marketing.

Now, for any given night or hour, he can break down his clientele by sex, age, ZIP code or other characteristics. If he wanted to, he could find out how many blond women named Karen over 5 feet 2 inches came in over a weekend, or how many of his customers have the middle initial M. More practically, he can build mailing lists based on all that data ? and keep track of who comes back.