LOS ANGELES — Like most superheroes, Joshua Fisher lives a dual life. During the day, he is a development executive for an animation studio and the father of two boys.

But at night, Fisher becomes Mayor DaMan, running the streets of Urbanville, setting interest rates, chairing community meetings and overseeing battles.

On a suburban street in Van Nuys, an L.A. neighborhood in the heart of the San Fernando Valley, Fisher and his next-door neighbor Barry Collier have created an interactive universe, Urbaniacs.com, filled with hip-hop music and bell-bottomed superheroes.

Over the last year, Fisher, 36, and Collier, 29, have spent nights and weekends building and developing this quirky virtual rabbit hole — and tens of thousands have followed them.

Through word of mouth, the site has become a choice destination for teens, who register free. The same urge that sent millions to Neopets to foster and feed virtual animals is sending teens in droves into this immersive realm. In Urbanville, they design a virtual personality, or avatar, who does their bidding. Registrants can train their characters in martial arts, spend "urbos" currency on gold tire rims and write rap songs.

Urbaniacs has hit a cultural nerve. In eight months, with no advertising, more than 30,000 individuals have become residents of Urbanville. Last month, 3 million visitors passed through the virtual community to play games and participate in message boards.

Fisher and Collier say they lose about $400 a month maintaining the site. But they are scheming to make Urbaniacs more than just a complicated hobby.

In January, the partners announced a deal with mobile phone publishing company Smartphones Technologies Inc. They want to deliver custom hip-hop and funk ring tones, video clips of Urbaniacs street battles and some of their many Web games to users through cell phone carriers.

"We love doing it, but we've made so many sacrifices to our wives, our families and our sleep patterns that we really want to be able to just do this full time," said Collier, who previously headed the programming department at Neopets Inc., which along with Pokemon trading cards has served as a model for Urbaniacs.

Collier and Fisher say that when they first met in front of their houses, they quickly hit it off and began talking about developing toys together.

"We saw we had the opportunity to create something more than a toy," Fisher said. "But instead of a physical toy, we built a virtual world that the toys could actually live in."

Having created the world, the partners now want to develop products — such as Moocho Macho Hombre dolls and Lunar Moonbeam Princess T-shirts. And they want the products to be played with and worn in Urbanville as well as the real world.

Some wonder whether Urbaniacs' goofy sensibility can evolve into real dollars.

"I'm not sure that I appreciate why somebody needs an avatar," said Michael Pachter, an analyst with Wedbush Morgan Securities here. "The question for these guys is, what do they want to be when they grow up?"

The partners are confident that their fast-growing audience will translate into money. They estimate that 50 percent of the site's users are ages of 13 to 18. The average Urbanville resident spends five hours a month on the site, and Fisher and Collier are constantly evolving this world to keep that resident there.

"As we grow from 30,000 to 300,000 to 3 million, that is a lot of eyeballs, and I know advertisers are looking for ways to connect with these viewers outside of television," Fisher said.

Urbaniacs is one of hundreds of popular sites on the Web that cater to young audiences. But it has combined the social communities of MySpace or Friendster with the interactive amusement of online gaming portals Pogo.com and GameSpot.

"It's not much of a stretch to go from MySpace or PureVolume to a world where you're represented by an avatar," said Eric Garland, chief executive of Los Angeles market research firm BigChampagne, which analyzes digital media.

Garland sees Urbaniacs as a pioneer in the U.S. in the trend toward online avatar communities, which have been popular in Asia for several years.

"People want more than passive and programmed entertainment," he said. "I think it's clear we're going to see more and more varied iterations of this."