National Alert Registry is a site that helps you locate registered sexual offenders in your neighborhood. It is a free website with nation-wide coverage. It also provides alerts via email/text message when a registered predator moves into your area. I recommend everyone with children signup for this service.
Just a word of caution. Remember these are the Registered offenders. Only 1 in 4 (25%) obey the law and are registered. That means 3 out of 4 or 75% are not being tracked. Also, remember a lot of child predators have not been caught. On average, if caught they have already committed another eight(8) crimes.