I would think parental supervision over possible violation of someones rights could keep child molesters from finding victims. I completely and totally agree that people who prey on children are dispicable and probably should never get out of jail due to the recitivism rates.
Just think an ounce of prevention on the parents parts would keep us from having to cross the moral line ourselves to give them a pound of cure.
That might work for the parents who are able to completely supervise their childrens online activities (how do you monitor those activities at a friend's house, or even at the library?), but I'm not willing to cede the innocence of those children whose parents are too stupid to give a damn. As for crossing the moral line, in a civilized society, we surrender our right of revenge to a collectively issued solution to the problem, with safeguards for the innocent built in. Obviously, that's not working, and the only way the ACLU hand-wringers will agree to incarcerate child molesters for lifetime periods is if there is enough of a chance they will die a horrible, painful, lingering death if left to people who truly understand what justice they deserve.