More than half of U.S. teenagers who are online keep in touch via online clubs called "social networks

To hear people talk about one of the hottest online phenomena, every American teenager is sharing stories, photos, and personal information on so-called "social networks." That's a stretch, but apparently more than half of the kids with access to a computer have set up personal profiles on sites like "MySpace" and "Facebook." The cable network MSNBC calls them "sort of a cyber combination of a [school] yearbook, personal diary, and social club."

The latest survey by the Pew Internet & American Life project found that 55 percent of online young people ages 12 to 17 are active on these sites, often several times a day. That means tens of millions of kids are enjoying what was a niche activity at best just five years ago.

Pew found that nine in ten social-networking teens use these Internet sites to stay in

Cybercrooks -- and even pedophiles -- can and do break into computer conversations far more easily than they intrude into physical homes.  And the consequences can be ruinous

touch with close friends. Older boys more than girls like to make new friends. And boys, in particular, admit to using the sites to flirt.

The Pew Project did not delve into two related issues that are giving parents nightmares: Kids passing around too much information and inappropriate photos showing real and simulated sex, apparent drug use, binge drinking. and predatory browsing by seemingly innocent teens who are really adult sexual deviates and identity thieves.

An Internet lawyer told MSNBC he found chatty teens blissfully sharing their addresses, cellphone numbers, and even class schedules online. All the while, some of their parents, according to this safety expert, were, to use his word, completely "clueless" that any of this was going on.