The biggest tycoon inside Second Life is Anshe Chung, a real estate speculator who also runs her own currency exchange. (The rate hovers around 250 "Lindens" to one dollar.) Linden does not sell the currency outright but gives members a monthly allowance; they are free to earn more through transactions with others inside the virtual world.

Other residents have quit their real-world jobs to run businesses inside Second Life. Chris Carella, the managing partner of Future Prototype, a three-person consulting company, started as a researcher at the Institute for Security Technology Studies at Dartmouth College. With a grant from the Department of Homeland Security, he redesigned Unreal Tournament 2003 - think a video game combo of "Gladiator" and "Mad Max" - into a training scenario for emergency response teams.

"We pulled out the guns and gave them fire hoses," Carella says.

Now, he's working on two different educational projects for teenagers inside Second Life. Future Prototype is helping create 3-D elements of an interactive global warming game designed by LexIcon Systems of Sharon, Vt. The National Science Foundation is providing a small business innovation research grant.

With the Urban Anthropology Project, which runs an after-school program for low-income kids in sixth to twelfth grades in Chicago, Carella is building a virtual environment for teens inside Second Life called Dream Learning Labs. In addition to Chicago, schools in Panama, Tokyo, and by the end of year, Israel, will each have their own island.

The kids will be encouraged to display their digital photos and interact with other cultures. "We'll help build the environment and mentor some kids," Carella says. "The larger goal is to teach them how to build 3-D objects and program a little bit."