Visit the Homepage of "Giving Something Back"
If you need to find someone who moved three to six months ago, there are CD-ROM products. One which I find useful is "Select-PHONE." If I recall correctly, the software and 5-disk US database cost between $100 and $200. They also sell data for Canada, Australia, 800 numbers and a European business directory. See your local software store, or do a search at the Internet Sleuth, in the Software category. If I've mis-remembered the price, get back to me. There are other providers.
If you know a phone number for your party but they don't want to talk and won't give you their address, then you've got a little different problem. Think about precautions recommended elsewhere in this article, before you blunder in. However, you may find their address from what is called a "Reverse Phone Book" at the reference desk of a large city library. Though I have not personally used it, one poster to the Internet Sleuth identified the "Cole Directories" as a source. Some on-line sites also do reverse phone search. One site which includes reverse search and other gateways to several email, phone, and address search engines is The Ultimate White Pages .
I should mention one category of off-line people search which is familiar from service with the US military. If you need to find a family member in any of the Armed Forces or the Coast Guard, start with a local office of the American Red Cross. They have long offered a family emergency locator service.
An alternative is to inquire with one of the military locators supported by the services themselves. You can reach the service Departments through the general information number at the Pentagon, (703) 545-6700. Ask to speak to an office affiliated with the service Personnel Command, and explain what you're trying to do: you want to pass a message to your relative, inviting him or her to get in contact with you. In the past, US Government agencies have been restricted from invading the privacy of their members by giving you an address without permission. Even if this continues to be true, they should be willing to pass your message on. Plan to wait a few days.
Several Internet sites also specialize in military affairs. Credit for these links goes to Curt Davis cdavis@syspac.com, one of the Internet Village Elders at the Sleuth.