Navigational search engine HopStop is letting advertisers hyper-target consumers via Ringleader Digital's third-party ad serving platform.

Ringleader will serve the ads for HopStop's WAP site. Users who visit HopStop's mobile site receive SMS ads that correlate to their exact location.

"[Ringleader and HopStop] are both publishers and advertisers," said Bob Walczak, CEO of Ringleader, New York. "A lot of our advertisers are very sensitive to location and that's why we are creating a valuable option for advertisers looking for location-based targeting features.

"As the mobile advertising industry continues to grow, it's becoming more valuable to be able to target based on consumer location and interests while still ensuring ad relevancy," he said. "Our model is able to do that."

HopStop provides users with door-to-door directions to city residents and tourists via public transportation systems. The site also allows users to search for places to eat, drink, sleep and sight-see in its City Guide.

HopStop services are available in New York, Boston, Chicago, San Francisco and Washington metropolitan areas.

The HopStop WAP site is formatted for mobile, which allows users to obtain directions directly from the mobile browser or receive them in a text message.

Ringleader gives brands and publishers the ability to distribute ad campaigns across any mobile digital platform.

Ringleader's advertising platform takes the location data of the user and identifies the advertisers in the immediate area or one along the way.

In addition, ads may also be served in response to the nature of the place the user searches for, such as museums, restaurants and shops.

Instead of flooding the user's mobile inbox, the advertisements served are limited to a single SMS message, ultimately lowering the costumer's mobile bill.

HopStop was named one of Time magazine's 50 Coolest Web sites of 2006 and was also named to Travel + Leisure's Top 25 Travel Web sites of 2007. The company claims to have nearly 1.7 million visits, 10 million page views and 30 million ad impressions per month.

"This is speaking to a different advertiser," Mr. Walczak said about the HopStop WAP site.

"There are large and national brands, and [there are] local brands," he said. "This should drive revenue from local businesses. If you orient an advertiser around the user's location, it helps attract local advertiser's money."