Whether you are trying to track down lost family members or surprise old friends, it is fairly easy to find someone's address for free using the power of the Internet. There are many resources available online, although you may have to check multiple sources and use a little bit of diligence. Still, it will be very rewarding once you get back in touch with family and friends.
Gather all of the most current information you have on the people you're trying to find. Even though you may have lost touch with them in recent years, knowing where they've been recently, as well as any recent name changes due to marriage, divorce, and so on, will help.
Use online white pages. WhitePages has a comprehensive white page listing, but there a few other sites, including Spokeo, that feature decent white page listings, as well.
Look into other personal information sites. If the traditional white pages aren't getting you the information you want, places like Zaba Search can scan public records (such as home sales) to find someone's address. Note: Although these sites use public records, they are not always accurate, and if someone requests that his information be removed, it will be.
Check around popular social networking sites. Many people use sites like LinkedIn, Facebook and MySpace to connect with old friends and lost family members. Simply searching for someone's name could lead to a connection (and a possible address).
Use a search engine. This is an inexact method, since simply typing a name into a search engine can often yield imprecise, outdated or falsified information. However, if you have had no success with the other methods, it is worth a try.