A few days before Halloween, 19 year-old William Freund, from the Ocean County CA area, killed two people and wounded at least one other. He had poor social skills due to a disorder, "Asperger's syndrome" (do the research), he had. He was picked on at school, in his community, and even on the internet (messageboards, forums, etc..).
Upon reading a few details about the story, some people on at least one particular website messageboard did a doubletake. "19 years old male.. shotgun.. Orange County area.. social outcast/autistic.. Wait a minute.... Holy Shyt!!"
They soon realized that this was the same person who had asked for advice about buying a shotgun. They had also made fun of him, on their messageboard.
Now there'll be the usual flurry of news sites and "experts" stating that "these websites" "are a danger" and will "need to be shut down immediately". And how website operators have a "responsibility to report" when someone posts a threat.
But the truth is, just because you post something doesn't mean you're really going to do it. Out of the hundreds and thousands of things I've read that people have posted online, I've heard of a lot less than 1% about in the news. Many people use the internet as a release for their stress, thoughts, dreams, nightmares, etc..
There's a freedom on the internet because of the anonymity granted by it. You're at home, typing, no one is around you, so you might feel a strength from it.
We, as humans, have almost always pushed away anyone/anything that's different. We don't embrace our differences, we shun them. Make them outcasts. Then after something happens do we say "We should have said/done something."
Now let me go off on a tangent on how/where these outcasts meet...
Many people have anonymous cyber sex in internet chatrooms. Some people fantasize about killing, or even being killed. Lots of people fantasize about being vampires, time travellers, celebrities, or whatever.
This is nothing new, before the internet, there were phone party lines, phone sex numbers, and other anonymous methods via phone lines. And there still are. There has always been writing. People write to relieve stress. They mail things to other people, magazines, celebrities, etc.. There are places people go to meet other people who are interested in the same activities. Vampires go to vampire clubs, Goths go to Goth clubs, people into S&M go to S&M clubs, gay men go to gay clubs, Wiccans (aka "witches") meet up with other Wiccans, etc.. There's nothing stopping people from meeting people with similar interests. Except the "mob" that usually shows up with signs, pitchforks and torches to stop them. Forcing the outcasts to relocate.