(FORTUNE Magazine) – Ever wonder where in California is home to the greatest concentration of German Americans with a household income of $45,000 or more? Well, you would if you were running the West Coast ad campaign for Lufthansa -- and you'd probably be happy to pay for the arcane tidbit. That's the hope of the folks behind Rezide, an encyclopedia that profiles all 42,496 zip codes in the U.S. Rezide, which is produced by Claritas, a computer-based market research firm in Alexandria, Virginia, has 122 stats for each zip, ranging from income to number of bedrooms. Says Claritas CEO Gary Hill, 54: ''If you're trying to find a person with particular attributes, we can point you to his doorbell.'' Companies such as Spiegel, a catalogue king and retailer in Downers Grove, Illinois, use Rezide information in their target marketing and direct-mail campaigns. Though Rezide is sold in book form, the real action comes from the CD-ROM or magnetic tape that allows you to do custom searches. Dom Perignon salespersons might like to know the five zip codes with the highest median household incomes (see chart). Surprise! Beverly Hills 90210 of TV show fame comes in 74th, with $93,756. The winner, Techny, Illinois, and No. 4, Kenilworth, are both neighbors of Chicago. Claritas has more sophisticated products that cost hundreds of thousands of dollars, but Rezide, which is made for small businesses, sells for $895 in book form or about $10,000 on CD-ROM. Or you could ask Claritas to do a custom-screen for you, starting at $75. Oh, and for the most German Americans per capita in a zip code, go to 95242, Lodi, located some 25 miles south of Sacramento.

CHART: NOT AVAILABLE CREDIT: NAI LEE LUM FOR FORTUNE CAPTION: RICHEST ZIP CODES