After consumers provide rent information and ZIP code, the new tool calculates the mortgage-payment equivalent of their current rent, along with some similarly priced Prudential Real Estate listings in their desired neighborhood.

To drive usage, the Prudential Financial unit has launched a digital ad campaign targeting renters and first-time home buyers on high-traffic Web sites like ApartmentGuide.com, Hotpads.com, ApartmentFinder.com, Realtor.com, Rentals.com, Truila.com, and Yelp.com, along with various lifestyle sites.

No doubt, the campaign's target audience would have benefited from such a service prior to the nation's fantasy-fueled subprime mortgage crisis. That does not mean, however, that consumers would not benefit from the "calculator" going forward, according to Earl Lee, president of Prudential Real Estate and Relocation Services.

"Housing affordability stands near all-time highs thanks to declining home prices and historically low mortgage rates," said Lee. "Now is the time to find out what you can buy."

The San Francisco-based Dapper helps advertisers automatically serve contextually sensitive display ads assembled from creative elements pulled from their own Web site, product inventory data, or any database of marketing offers. A fashion retailer, for instance, can associate each item of its product catalog with a particular weather condition. Then, if a user is viewing an ad from a geographic location where the weather is sunny, they will view "sunny" items like T-shirts and beachwear.

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