(Fortune Small Business) -- Despite his wheelchair, and often because of it, Dr. Glen House has always enjoyed doing what he isn't supposed to.

Take the time he persuaded his neighbor in Colorado Springs, J.W. Roth, to join him on vacation in the ice fields of Taku, Alaska. The trip entailed flying to a remote lodge in a tiny ski plane that was ill-equipped for disabled passengers: Boarding was via a rope ladder. "They said no wheelchairs," Roth recalls. "So we signed up."

That 2006 trip was a turning point for House and Roth. The boarding process was dicey: Roth gave House a fireman's lift up the plane's ladder, which dangled over the ice. "If I go down, you're going with me," House snarled on the way up. But later the pair sat in the Taku lodge, wondering how they might bring such exhilarating experiences to other disabled people. "They're sick of doctors," House told Roth. "They want to know how to live forward with their conditions."

That chat led to this year's launch of Disaboom.com, a fast-growing social network aimed at the 50 million Americans with disabilities and their caregivers. In a time of social-network fatigue, as Facebook and MySpace have spawned hundreds of bland imitators, Denver-based Disaboom is unique. It focuses on a large, untapped audience eager to get answers and make connections, and one that advertisers had previously been unable to reach.

Like the entrepreneurs in the stories that follow, House demonstrates that disabilities are no obstacle in the brave new world of technology. If anything, the determination they engender provides a clear business advantage. According to the U.S. Census Bureau, the percentage of self-employed Americans with disabilities has grown from 12% to 15% since the dawn of the Web. For the rest of us, the figure has stayed static at 8%. Your next competitor may just zoom past you in a wheelchair.

When House wants to get somewhere, he goes fast. "That is how I ended up in the wheelchair," he says. During a ski vacation in Snowbird, Utah, House ignored the sign that read DANGER! ROCK! and at 20 became a quadriplegic from the pectorals down.

But House lost no time pursuing his next goal: He began studying for medical school. His Disaboom colleagues all have stories of his dangerously fast driving; one had to pull him from his car when it skidded off the road into the Colorado snow.

House is the public face of Disaboom, writing most of the medical guides to the 40 disabilities the site covers and participating in its forums. It doesn't hurt that he and Roth founded the company last year just as the Fox drama House, which features a partially disabled doctor named Greg House, started winning over critics and viewers. Glen House was not the inspiration for the show, although at least one patient insisted on his autograph anyway.

It helped that Roth, one of the founders of biotech firm AspenBio, came aboard as CEO. Roth swiftly garnered $15 million in funding and began targeting advertisers. By April, Disaboom had racked up $1 million in ad sales to corporate Godzillas such as Ford (F, Fortune 500), Avis (CAR, Fortune 500), Johnson & Johnson (JNJ, Fortune 500), and T-Mobile, and had served up 23 million online ads.

Roth launched a sister site, Disaboomjobs.com, in an effort to address the 60% unemployment rate among disabled Americans. He even bought a disabled-dating site called lovebyrd.com.

"We don't want Disaboom to smell like a doctor's office," Roth says. "We want to deal with dating issues, sex issues, how to drive a fast car."

Disaboom officially launched in January. The main site now boasts 72,000 registered users, and the rate at which new users sign up is growing by 500% a month. In March presidential candidates Barack Obama and John McCain both launched profiles on the site. Roth and House maintain folders full of thank-you e-mails, many from parents of disabled kids who didn't know where to turn until they found sympathy and suggestions from the Disaboom community.

The site is not without problems. Roth decided to take Disaboom (DSBO.OB) public before its launch; as of late August, the stock was trading at an anemic 50 cents a share, $1.30 off its 2007 high. One disabled blogger at GearAbility.com complained that Disaboom jobs listed too few positions specifically for the handicapped, and that much of the content read like PR blurbs.

"There's a lot of buzz about them," says Jennifer Simpson, senior director of technology policy at the American Association of People With Disabilities, a lobbying group in Washington, D.C. "We talk about them all the time, but I don't think they're where they want to be."

House and Roth are working on that. They recently struck deals with the Mayo Clinic and Harvard Medical School to license a reliable range of medical content. With $4 million cash in hand, Disaboom's stock slump isn't going to bite anytime soon. The 39 employees on staff include three full-time "social marketers," who write blogs and help promote the site on a range of popular websites such as Digg and Twitter.

"This is the tip of the iceberg," says Roth at his conference table in a suburban Denver office park. He already has plans to launch other social networks for underserved markets. Neither he nor House will say more than that, but it seems likely that they'll soon be doing something they weren't supposed to do, one more time.

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