neither of my kids have a Myspace account. I control their email account, and I set the password - they cannot change it. They know if I found something inappropriate, I would change it so they couldn't log in!
NL can be a computer "addict" at times, so he is ONLY permitted to use the laptop while sitting next to me (unless it's homework related - and I'll take the Wifi card out before he gets the thing). He's done nothing stupid so far, he just wastes time on it.
As long as they are in my house, using my connections, they follow my rules. Even though NF is out of the house, his "home" email is still an offshoot of mine, so he still has to follow my rules. Of course, his other is a military email - and he better follow the rules on THAT one!!!