The Goverment's National Sex Offender Public Website
If you are looking to locate a sex offender, the United States Department of Justice offers the Dru Sjodin National Sex Offender Public website at nsopr.gov. The site allows one-stop access to sex registries from all 50 states and the District of Columbia.

Here are some helpful tips for using this site, courtesy of the government:

• State sex-offender registration and notification programs are designed to give you information about persons convicted of sexual molestation or the sexual exploitation of children, as well as persons convicted of rape and rape-like offenses (regardless of the age of the victim).
• Use the site wisely. The department makes it clear that the website is a public service and therefore the department isn't responsible for any inaccuracies.
• Verify information. The department recommends getting in touch with the responsible state agency or local law enforcement agency where the offender you seek resides, works or attends school.
• Be aware that states participating in this government website have their own information collection and privacy/confidentiality policies. The policies are spelled out on the site, state by state. For example, a given state may limit public disclosure over its website of information concerning offenders who have been determined to be high-risk, while another state may provide for wider disclosure of offender information, but make no representation as to risk level of specific offenders.