People search
These are generally of use almost entirely for the United States. I've included quite a few as the quality of results tends to vary - different ones are better for different searches, with no obvious consistency.
People-search tool for US
US public data search. Formerly known as Cubib
People-search tool for US
People-search tool for US. Looks for social media accounts as well as basic info
People-search website. Has reverse address search
Background check site. Emphasis on legal records. Includes reverese address search but free info very limited