A tinkerer since childhood and an entrepreneur since he was a teenager, Philip Rosedale was always captivated with the idea of simulated reality and imaginary environments. He worked as CTO of RealNetworks until computing technology caught up with his fancies. Then he founded Linden Labs and built a virtual civilization called Second Life. That environment now boasts milions of citizens and a buzzing economy (currency: Linden dollars) that represents over $10 million in real value.

Second Life may be artificial but it's hardly trivial, Rosedale says. Its appeal to human creativity is obvious, but beyond the thriving in-world industries and bustling social spaces, real-life businesses (and even some religious organizations) are using Second Life as a platform for meetings, services and collaboration.

"You can imagine New York City being kind of like a museum," Rosedale says. "Still an incredibly cool place to go, but with no one working in those towers. You are going to [work] in a virtual world."