Allan Grant met his company's co-founders, Jeff Yee and Nori Yoshida, at a bar. The three software developers immediately bonded over their interest in lean start-up principles and Ruby on Rails, a programming framework. After months of coffee shop meetings and late nights discussing software code, the three decided to take their work relationship to the next level. They moved in together—temporarily leaving their spouses behind—and devoted all their time to launching their company, Curebit, which makes software that lets businesses offer discounts to customers who recommend their products on Facebook.

It is no wonder that Curebit's story sounds like a kind of strange romance. The company's creators met through FounderDating, an event in San Francisco and Seattle that is designed to help aspiring entrepreneurs meet potential co-founders and hone their business ideas. Entrepreneurs, many of whom are interested in launching tech companies, typically go to functions like these to meet people with skills complementary to their own. To maintain a balance of technical and business experience among participants, FounderDating is selective about who may attend. Entrepreneurs must fill out an online application, answering questions about their experience, interests, and area of expertise. Each event is capped at 50 attendees, who pay a small entrance fee—typically less than $50. "We put a lot of work into screening people," says Jessica Alter, FounderDating's co-founder. During the three-hour gatherings, entrepreneurs form groups based on their area of interest—say, enterprise software or mobile applications. So far, FounderDating has held 10 events and yielded several start-ups.

At another event, Startup Weekend, entrepreneurs not only meet potential co-founders but also work with them. The event challenges aspiring entrepreneurs to work together to develop new businesses in three days. Participants, who typically pay from $75 to $99 each, present 60-second pitches in hopes of recruiting a start-up team. The attendees vote for their favorites and then break into teams to help the entrepreneurs with the top business ideas. Over the course of the weekend, the groups refine business models, create mockups, and often launch actual businesses. Since 2009, Startup Weekend events, which are held in 120 cities worldwide, have spawned more than 180 companies. Several of the businesses, including Memolane, a San Francisco–based site for archiving photos and updates from sites such as Facebook and Foursquare, have received funding.

Jameson Detweiler and his partners, Stephen Gill and Dave Drager, worked throughout the first night of Philadelphia's Startup Weekend, held in January, in order to open LaunchRock, a service that creates souped-up "launching soon" webpages for start-up customers. By 12:30 the next afternoon, the site was live. "By pumping it out, we could get feedback that we wouldn't have gotten otherwise," Detweiler says. It was also an effective test of how well the partners worked together under pressure. A few weeks after the event, the group had recruited another co-founder, Zachary Melamed, and was in the process of incorporating the business.

Most events aim to provide participants with a pool of potential partners, rather than immediate, one-to-one matches. "You don't expect to leave the event perfectly matched," Alter says. "That's like going to a party and leaving married."

Nichiketa Choudhary and Michael Ossareh took it slowly after meeting at a FounderDating event in San Francisco and discovering their mutual interest in developing a system to improve employee performance reviews. After the event, they met regularly to brainstorm. Often Choudhary's husband and Ossareh's girlfriend would join them for dinner. "Your business partner becomes a key part of your life," Choudhary says. "You have to make sure that person works with your extended support network." Six months after they met, Choudhary and Ossareh incorporated their company, Rah, and began working on it full time.

In some cases, one's first match may not be a good fit. Alexa Andrzejewski attended a Startup Weekend event in San Francisco to develop her business idea: a mobile application for browsing and rating restaurant dishes. By the end of the weekend, she and her partner, Michael Goff, had come up with mockups of a mobile app called Foodspotting, complete with restaurant profiles and images of meals. Andrzejewski's demo was so effective that Dan Martell, an angel investor in attendance, offered her $5,000 in seed funding that evening. But she and Goff soon parted ways. Andrzejewski says the two of them disagreed on Foodspotting's overall vision; Goff says they weren't able to agree on ownership terms.

Even though the partnership fizzled, the event was beneficial, says Andrzejewski. She continues to tap the contacts she made at Startup Weekend for advice. Plus, the funding she received at the event helped her persuade Ted Grubb, a software developer she had previously consulted, to join the company full time. Since its launch last January, Foodspotting has amassed more than 650,000 users and gone on to raise nearly $4 million in additional funding. "I was able to soak in feedback and pick people's brains throughout the weekend," says Andrzejewski. "That's really the most valuable part of the experience."