Well, I just read the last 2 pages of this thread. I have mixed feelings. I know what dangers are out there. My kids are grown up (24 and 26), but were extremely computer savvy at young ages. I also spent 30 years around middle school and HS kids.
But... I am a child of the sixties/early seventies. I was treated as a responsible adult as a teen. My parents trusted me and I could always tell them anything, even if I didn't. Did I do wild stuff? Sure. According to some of my former co-workers, I should be dead or burning in Hell for some of the stuff I did. I smoked weed, hung out on the Boston Common, and I ah, liked boys, too. Never did drink, though.
I never was shocked by what the kids at school were saying/doing when I taught, because I did almost all of it when I was their age. My own kids had a lot of freedom compared to their friends, but they also had a lot more responsibility; they worked, had to do stuff in the house, pay for their gas, etc. I didn't let them sit in my car at the end of the cul-de-sac, waiting for the bus. They stood out there in the rain (with an umbrella).
When my oldest son was 12 and in 6th grade, he asked me to drive him to the mall to meet a "girl" he had met on line. This was in 1994 or 95 and not too many kids were meeting people on line. I knew right away he was probably talking to some perv and I said no. We had a little chat and that was it. Yeah, that one spent too much time IMing, when I thought he was doing his homework, but he did manage to graduate with honors from college. I caught the younger one looking at porn when he was in 7th grade, on my computer. He was so embarrassed, that never happened again.
I don't think I would troll my kids Facebook accounts after an initial discussion of the dangers, etc.
My motto was "talk to them about everything." I guess it worked, because my kids never got in any trouble as teens. They were/are not geeks, and are socially responsible people.