The listings are customized to the user’s most recent search for homes, down to the neighborhood, home size, price range and attributes.

The ads, dubbed Home Page Featured Listings, features three graphical ad units at a time – two sponsored by national brands and one sponsored by a regional brokerage. Because the ads are targeted to a user’s most recent search (versus their geographic location), advertisers are able to target all buyers, including those who may be relocating or purchasing a second home, the company said.

“At Zillow, we recognize that in today’s challenging housing market, national and regional brokerages need performance-based online advertising solutions that deliver real results for their agents and sellers, while strengthening brand awareness,” said Greg Schwartz, vice president of ad sales at Zillow. “Zillow’s new Home Page Featured Listings are another example of our commitment to providing high value, high return advertising solutions for real estate advertisers.”

Century 21 is the first national brokerage to sign up for the program. Zillow.com gets more than 8 million visits a month.

The product allows clients to purchase 25%, 50%, 75% or 100% of the available ad views on searches for homes within a given zip code. Showcase Ads are an expansion of Zillow’s first local advertising product, EZ Ads, a platform that more than 13,000 local advertisers nationwide have used since the product launched in April 2007.

“Zillow is committed to offering local professionals affordable and easy-to-use tools to get in front of our large audience of consumers interested in real estate and buying and selling homes,” said Greg Schwartz, vice president of ad sales at Zillow.com. “We strongly believe that the more targeted an ad can be, both at a national and local level, the more useful the consumer will find it and the more successful the advertiser will be.”

Launched in early 2006 with Zestimate values and data on millions of U.S. homes, Zillow has since opened the site to community input, data and dialogue.