Open Records

http://www.openrecords.org/ is a clearinghouse for all types of government-released records and reports, available to everyone.

They do have one section that does help those who are looking to move to a new city or neighborhood, and that is a link to US States Sex Offenders Registries, as broken out into both a national registry as well as state-by-state.  Not all states report information in the same way, but you should be able to pull reports by ZIP code for most of them.

 Other helpful databases linked here include the HOLOCAUST SEARCHABLE DATABASE, DALLAS RESTAURANT HEALTH SCORES, and a list of STOLEN IRAQI ARTIFACTS.  Sure, some lists will be more useful than others, but the concept is the same.