Starbucks is experimenting more with location-based social networking websites as it seeks to connect with tech-savvy customers.

The Seattle-based coffee giant is expanding its relationship with popular websites Foursquare and Brightkite, which let people “check in” at businesses and other places on their mobile phones and share their location with friends.

Starbucks is already a prolific user of Facebook and Twitter to build brand awareness and customer loyalty. But the new crop of location-based services is particularly appealing for the coffee giant because they draw people to the company’s stores.

“We are very interested in location-based services because we are primarily a retail-based business and haven’t discovered a way to make a cup of coffee over the internet,” said Chris Bruzzo, Starbucks vice president for brand, content and online. “Location-based services are perfect for us, and we’re really excited about the possibilities that this presents.”

Starbucks already offers Foursquare users who check into five different Starbucks stores a virtual “barista badge.” Now the company is considering what kinds of real-world rewards to offer people who frequent Starbucks stores on Foursquare.

The coffee giant said it’s not ready to announce Foursquare rewards yet, though Bruzzo said they could potentially be tied to product launches, “mayorships” (when people get crowned “mayor” of a location for visiting it more than anyone else), or perks for Starbucks cardholders.

Starbucks is engaged in a heavy marketing push for its milkshake-like Frappuccino drink, and is promoting the drink on another location-based site, Brightkite. Brightkite users can earn a Starbucks badge if they check into a store during Frappuccino “happy hours,” when the drinks are half-price. (The promotion is 3 p.m. to 5 p.m. on weekdays, and runs through May 16.)

To prepare for more extensive use of Foursquare, Starbucks is loading all of its 6,700 company-owned U.S. store locations into Foursquare’s database and eliminating duplications from users who have entered multiple names for the same store.

Ross Rubin, executive director of industry analysis at NPD Group, a market research firm in New York, said Starbucks could potentially use location-based sites like Foursquare in a variety of ways.

“There could be different kinds of bonuses from coming with your friends or having meetings there,” Rubin said. “There are opportunities to promote new beverage items and menu items.”

Foursquare, Gowalla and Brightkite are among the location-based sites vying for people’s attention these days. Social networking giant Facebook is also planning a feature that lets users share their location, though the full details haven’t been released yet.

Interestingly, McDonalds — a growing competitor for Starbucks in the coffee business — is working an application with Facebook that would let users check in at McDonald's restaurants, according to AdvertisingAge.

Starbucks has its own iPhone apps that locate Starbucks stores and let people swipe a barcode scanner with their iPhones to buy coffee (a feature currently limited to select stores in Seattle, Silicon Valley and and some Target stores).

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