I keep tabs on the known sex offenders in our area, but the truth is the unknown sex offenders in any given place far out number the known ones. Consequently, we focus on the children in our neighborhood and we speak up about any potential grooming behavior.
That said, if I know or strongly suspect that someone is a child sex offender, I go to the police about any possible violations such as hanging around playgrounds. I speak up about them within their hearing expressly to make them uncomfortable, hopefully uncomfortable enough to leave town. I tell others what I know, whether they have children or not. I notify everyone who has a legitimate reason to be around children (librarians, park workers, teachers, nannies, ice cream parlor workers, bus drivers, and the rest). Basically anything to prevent a tragedy, within the letter of the law, without rising to legal harassment or driving myself crazy. I don't go out of my way, I simply tell the people that ought to know when we happen to be meeting up for something else.
My child is too young to understand these dangers, though I've impressed on her to never wander off, never go with anyone else, and that sort of thing, but fortunately she's too young to be out of sight, too.
