In Iron Man 3, Tony Stark and his nemisis The Mandarin show off all the tech innovations yet to be invented. Among them: the ability to control a computer by moving your hand through the air. In one scene, The Mandarin moves through a digital projection of his brain using minute hand motions to pinpoint the specific region that senses pain.

What's science fiction to us, however, is day-to-day life for David Holz and Michael Buckwald, the founders of Leap Motion, which makes technology that lets users operate a computer by moving their hands in front of the screen.

How does it work? Users purchase a compact controller only slightly larger than an USB flash drive for $79.99, then download Leap's software. Inside the controller are infrared cameras that track all 10 fingers within the eight cubic feet of space in front of your computer. As long as the user's hands remain within that space, he or she can slash at fruit, move objects, draw, paint, browse the Web, and much more.

"This technology can be used in a range of categories, from gaming and education to drawing applications and 3D modeling," says Buckwald. "We're also looking at how it might be used in mobile and medical devices and cars."

Holz began developing the software back in 2008 while he was studying for a Ph.D. in mathematics at the University of North Carolina at Chapel Hill. Frustrated by the limitations of the mouse and keyboard, he spent nearly five years developing the cameras in the controller. By the time he paired up with Buckwald, a childhood friend and entrepreneur, Holz had a prototype.

Unfortunately, the prototype was huge and took more than an hour to set up-;not ideal for giving a demo to potential investors. But one angel investor, Avid Technology founder Bill Warner, was impressed. "The prototype was big, but the devil is in the details," he says. "It was amazing how the thing could track all 10 fingers at once. And it was amazingly fast with almost no lag time."

Warner invested $25,000, then worked closely with the founders for two years, helping them build their start-up and develop a product that they would want to use. "There was real money being dangled to do military work," says Warner. "But I encouraged the guys to think of who they love, and to make the technology for them--to build a direct relationship with those people rather than take the easy way."

As it turns out, money was never a problem. The company raised seed, Series A and B rounds totaling about $45 million from a group of angels and venture capital firms including Andreessen Horowitz, Founders Fund, and Highland Capital Partners. The company has grown to 80-plus employees, compared to just 12 about a year ago.

Leap's technology will launch in Best Buy stores in late July. The company has already accepted $10 million in pre-sales from its web site, without any advertising. "Forty-thousand developers signed up to make 3D applications," says Luke Nosek, co-founder of Founder Fund. "This was bigger than the iPhone and the Facebook platform when they launched. We were stunned."

Nosek thinks Leap's most impressive achievements are still to come. "With the computer as an automatic extension of our being, creativity will flow more easily," he says. "Video games, music production, even computer programming will change. I really think Leap is that transformative."