“Darn it, I’m not the mayor anymore!” exclaims Johanna Kramer, glancing at her BlackBerry as she sips a beer on the patio of The Federal in Durham.

Don’t worry. Nothing has happened to longtime Durham mayor Bill Bell.

Kramer, a social media consultant, is a devotee of the mobile networking service Foursquare, a location-based social network that has snowballed in popularity as the use of smart phones has increased. Launched a little more than a year ago, it now claims more than half a million users. The service allows users to “check in” with their GPS-enabled smart phones at restaurants, bars, stores and other establishments.

“I check in pretty much everywhere,” says Kramer, who reigns as mayor at 14 places, including the Harris Teeter on N.C. 54 and Jujube, the pan-Asian restaurant across the street in Chapel Hill. “To me it’s like a fun little game.”

Users accumulate virtual badges and points for checking in. The person who checks in most frequently at a given location becomes the “mayor” of that place. Users can consult Foursquare to see if members of their network are nearby, making it easy to connect with friends for bar hopping or group dinners. They can also share their tips and opinions on an establishment’s Foursquare profile.

Business owners are taking note, using Foursquare as a marketing tool by offering specials to mayors and users. In the Triangle, Foursquare users can find a slew of area discounts. LoneRider Brewing Company in Raleigh gives 15 percent off tasting-room beers to its mayor. The mayor of Cuban Revolution in Durham gets a free appetizer at lunch or a free dessert at dinner.

Tyler’s Taprooms in Durham, Carrboro and Cary offer a free order of garlic fries to anyone who checks in using Foursquare.

Ken Knoy, the manager at Sitti, an upscale Lebanese restaurant in downtown Raleigh, says Foursquare has been a great source of free demographic data.

“We’ll go on and see how many people have checked in,” he says. “We’ve found regulars we didn’t know were regulars.”

For Johanna Kramer, Foursquare is a way to make real-life connections with the large network of Triangle-area foodies she follows on Twitter under the name “Durham Foodie.” “If I check in somewhere and see that another local foodie is there, I would be inclined to go say, ‘Hey, I’m Johanna, I go by ‘Durham Foodie.’”

I’m not quite sold on the whole thing yet. But armed with my iPhone, I set out to see what all the fuss is about. My first stop is Foster’s Market in Chapel Hill, where I often like to relax with a cup of coffee and my laptop. I type “Foster’s” into the search box and come up with a “Foster’s Market” and a “Foster’s Markey.” Because location names are user-generated, Foursquare has some glaring errors reminiscent of early Wikipedia. I click the green “check in” button for the correctly spelled location and immediately receive an e-mail congratulating me for unlocking the “newbie badge.”

I add a tip. “Best scones in the Triangle!”

Next, I check in to Flyleaf Books, a new independent bookstore I’m hoping will survive. For my troubles I’m awarded seven pointsfive for a “first time” check-in and two for a “travel bonus.”

Then I check what my Foursquare friends are doing. All three of them. My brother has just checked into the Harvard Club of Boston, which is intriguing, since he lives in rural Vermont. Another friend is in Concourse B at the Atlanta airport. Another provides a bit of useful information: She has just declared her love for the chicken wings at the West 94th Street Pub in Durham.

I guess I need more Foursquare friends.

As it turns out, I may soon be able to skip Foursquare in favor of the hyper-local social network TriOut.

Launched in February, TriOut is the brainchild of RTP Web developer Lawrence Ingraham and Raleigh-based online marketing strategist Wayne Sutton. It is, in a nutshell, Foursquare for the Triangle area.

TriOut enables users to rate and review local businesses, giving it the feel of a mobile CitySearch or Yelp. Top users can win tangible prizes, like gift certificates to local restaurants. Some establishments have signed on to offer specials. The Dairy Queen in Morrisville is giving away buy-one-get-one-free Blizzards; Isaac Hunter’s Tavern in Raleigh is offering a “special reward” for every fifth TriOut check-in.

Though TriOut has about 800 users now, according to Sutton it’s adding people every day.

I’ll be an early adopter for once. I pull my iPhone out of my pocket and add the TriOut app.

Now about that free Blizzard …

The Indy’s new website also features Cocktail Compass, a free iPhone app that lists the nearest bars and drink specials.