When the 40,000 subscribers to Reason, the monthly libertarian magazine, receive a copy of the June issue, they will see on the cover a satellite photo of a neighborhood - their own neighborhood. And their house will be graphically circled.

On one level, the project, sort of the ultimate in customized publishing, is unsurprising: of course a magazine knows where its subscribers live. But it is still a remarkable demonstration of the growing number of ways databases can be harnessed. Apart from the cover image, several advertisements are customized to reflect the recipient's particulars.