Salvation Army
The Salvation Army offers a free family locator service. You can also look to see if a friend is registered at their Salvationist Directory.
Who? Me?
There are lots of free search engines here where you can find out if someone is looking for you!
The Seeker
Find out if someone is looking for you here. You may search and post messages for free. People can post messages looking for former classmates, lovers, neighbors, military buddies, heirs, relatives, missing people and such.
In addition to all of the public record resources and information you can obtain about people using the Freedom of Information Act, described on other parts of this site, feel free to check out these free people search resources.
Know of a site that belongs on this list? Contact Spies Online.