Now that online hangouts like MySpace and Facebook have blown up, a new crop of niche communities is riding the wave. In September, a Microsoft spinoff called Wallop.com launched with a VIP approach: only letting in people who have been invited by existing members. Founder Sean Uberoi Kelly says it's a necessary - and evolutionary - alternative to getting lost on big sites. "Wallop was designed for people who wanted something more exclusive and private," he says. "It mirrors the social norms of real life."

Call it the narrowcasting of social networks. Across the Web, there's an underworld of special-interest hot spots for surfers who share everything from ethnic background to playlists of My Chemical Romance. Each site boasts the basics - letting users create a profile and link up with other members - but wraps it in a more personalized experience. Here's a look at five favorites.

DOWNELINK.COM

WHO IT'S FOR The young gay comunity

MEMBERS 300,000

WHAT IT IS Founded by the three twentysomething college buddies from California State Polytechnic, the San Francisco-based Downelink fosters a different kind of gay network for young adults. It's open to the entire lesbian-gay-bisexual-transgender community, and it doesn't hype sex. "There is more to gay culture than the physical," says co-founder Danny Nguyen. In addition to giving members access to blogs and forums, Downelink keeps an updated guide to gay-friendly businesses, restaurants and news around the world. There's a new dating feature on the site, but explicit photos and ads get pulled. "We felt the need to create a safe space for young gay people to communicate about their sexuality," says Nguyen.

VAMPIREFREAKS.COM

WHO IT'S FOR Goths

MEMBERS 400,000

WHAT IT IS This hub for all things gothic and industrial got a burst of unwanted attention in September when a Montreal murderer turned out to be a member of the site. But a Skinny Puppy fan does not a murderer make, asserts founder Jethro "Jet" Berelson, a club kid from Brooklyn. "Just because someone goes around shooting people and happens to be a member of VampireFreaks doesn't mean that this Web site has influenced him to do such a horrible thing," he wrote. The site's forums - called cults - cover requisite interests, including Tim Burton, emo kids, and "girls who love gay guys." But the hottest draw is the revolving top-rated lists of boys and girls. Sixteen-year-old ouzo-swilling ferret enthusiasts from Holland seem to stand a good chance.

LAST.FM

WHO IT'S FOR Music fans and musicians

MEMBERS 50 millions

WHAT IT IS Unlike music-discovery sites such as Pandora, which use computer algorithms to create personalized radio feeds, Last.fm is powered by its people. Members log on for free, and their iPod or Windows Media playlists get automatically uploaded to the site. Last.fm uses the info to connect like-minded music lovers and lets them turn one another on to other bands. Co-founder Martin Stiksel, who ran an online record label before this site, compares the model to Amazone's recommendation system, but with a throwback, vinyl-record-store feel. "We're 100 percent totally socially driven," he says. "We put people in charge, and they're the experts. It's an old model."

BLACKPLANET.COM

WHO IT'S FOR African-Americans

MEMBERS 3.5 million

WHAT IT IS As the Web's fifth-largest social network, BlackPlanet is the center of the sprawling Community Connect - a dot-com in New York that's devoted to building ethnic sites. The company also runs AsianAvenue.com; MiGente.com, for Latinos; and, coming in December, a gay and lesbian site called Glee.com. "We make sure everything from our forums to our news is tailored to our members," says Community Connect representative Court Cunningham. "We're a more welcoming and engaging space." In October, BlackPlanet rolled out an expanded music selected, including streaming tracks from 175,000 artists, featuring Jay-Z and Janet Jackson.

GAIAONLINE.COM

WHO IT'S FOR Anime fans and gamers

MEMBERS 5 million

WHAT IT IS Founded by a group of comicbook artists in San Jose, California, Gaia is the place for fans of Japanese animation and video games. Part social network, part massive multiplayer game, Gaia lets members sign up for free and create their own pixielike cartoon characters. Once on, "Gaians" build homepages and Sims-style virtual homes, which they trick out using "gold" accumulated from time spenf online. This playful sense of personalization is key to building a sustained community, says CEO Craig Sherman. "We're tying in with a normal, deep human need to explore your identity," he says. "When you're a teen, it matters more than ever."