Film/TV (Dennis Crowley & Naveen Selvadurai)

Foursquare is the app even your friends who aren't tech geeks are using, precisely because they're not tech geeks. Its concept is decidedly unnerdy: Use your GPS-enabled phone to tell Foursquare where you are. The more places you visit, the more points you get and the closer you get to earning badges and mayorships. Your friends can leave tips on places to go, and bars, restaurants and stores can create specials for their most frequent patrons. Basically Foursquare quantifies our real reason for going out: scoring cool points.

So it's unsurprising that co-founder Dennis Crowley is out at a bar when I talk to him. "It's tough to get out of the office," Crowley says. But it's easy to stay out of the office too, since going out all night technically counts as product testing. Crowley and partner Naveen Selvadurai met while working for digital startups that shared an office space -- their desks were next to each other. They also shared what Crowley describes as "a mutual appreciation for the complexities of New York" and wanted to build something that made going out into a game and that their friends (other young, Manhattan-dwelling technophiles) would use, too. This past March, Foursquare celebrated its first birthday with almost a million users, and is rumored to be courting offers from a few tech giants ("We haven't made any decisions about anything," is Crowley's way of dodging the question).

The best part of being on Foursquare? The more points and badges you earn, the less you remember that you're using Foursquare. You just know you're going out and seeing friends more and more. But earning badges can become addictive. For instance, Crowley says they tested out the "specials" feature by creating one for the Foursquare offices. "We set one, 'If you check in nearby, swing over and say hi to Naveen and he'll buy you all your drinks tonight,'" he says. Someone finally came to collect. At 11 a.m. "We see all sorts of strange things like that," laughs Crowley. "People get kind of fanatical." They had to explain that the offer was just a test. But if Foursquare keeps finding new fanatics (and it will), then next time, drinks are definitely on them.

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