Where is a good place to start if one wishes to lookup certain people using public records?

There are a number of resources that can be used to lookup certain people using public records. Certainly if the interest is in tracking ancestors, sites like Ancestry have public birth, marriage, and death records. Social networking sites like Facebook can be searched to find individuals using search arguments such as name, hometown and school. Professional networking sites like Linkedin are useful for locating professionals using search arguments like name, location, and employer.