When your clients not only pay for your products but also have a hand in making them better, fostering that relationship becomes Priority No. 1. That's the case with Rally Software, a Boulder, Colorado, company that sells a software platform other businesses use to manage IT projects. The Rally platform, like the iPhone, becomes more valuable the more applications that are developed to run on it. For Rally, the question was how to get clients excited about its software.

Its answer: Bring out the tech geeks.

Software engineers are often kept out of view, but Rally makes them a key part of its marketing strategy. Earlier this year, Rally invited programmers from 14 of its client companies--including Cisco Systems, Level 3 Communications, and OtterBox--to Boulder for a conference on Agile software development and challenged them to create the coolest software program they could imagine using the Rally platform before the conference ended. The programmers were paired up with Rally software engineers for a two-day marathon code-writing session, or hackathon. Fueled by energy drinks, pizza, and beer, the teams worked side by side for the grand prize of an iPad for each team member, a 2-foot-tall trophy, and bragging rights.

Hackathons have been a staple of the tech community for a while now, but they typically don't involve companies working directly with their clients. The event gave Rally some one-on-one time with customers and let Rally's staff members talk shop with people who use the product regularly. "This was a great way to build relationships and get a candid look at how they use our product," says Todd Olson, a Rally vice president. For the clients, the hackathon not only posed a fun challenge but also gave them uninterrupted time to focus on whatever app they wanted to build, usually something that made their work life easier.

"It's a time to step away from the general backlog and push yourself," says Jack Yang, a vice president of engineering at vacation-rental company HomeAway.com. Despite hundreds of emails awaiting him, he refused to look at them during the hackathon session. "I told people I am not available," he says.

The experience of sitting next to a fellow developer and coding for two days straight creates a rare kind of camaraderie, says Becky Vereb, a developer from software maker Ansys. She flew in from Pittsburgh to compete in the hackathon. "It's an environment of people with similar interests and a friendly competition, and they're helping you build something you're interested in," she says.

Chris King, a developer from Cisco, decided to pursue one of the trickiest projects of the day: a complex app to track internal software-development projects and show a timeline of any code changes and progress. He was paired with Rally engineer Mark Smith. "This seemed like a fun project to test the limits," says King. "Half of it goes over my head, but luckily I have Mark here."

Smith and King worked 32 hours straight writing code before demonstrating their app on the final day. The crowd of 200 at the conference voted--and the pair won. In addition to the iPad, King got a new program to take to his managers.

Besides firsthand feedback on new software features, the hackathon brought Rally 13 new apps for its platform. Also, a number of clients, including Ansys and HomeAway, are using or improving on the apps created during the competition. Rally even sent engineers to HomeAway's headquarters in Austin to continue building the program that Yang started during the competition.

The hackathon did such a good job of bringing Rally's engineers and clients closer that the company plans to host hackathons regularly. Even several months later, Vereb says when she runs into problems and calls Rally's tech-support line, she will get calls back from people she met at the event. "It really put a face on the company," Vereb says. "And as nerdy as it sounds, I had a blast."