Here’s a nice link for a free address search:
Mellisa Data
For accurate, more in-depth searches, go to this link:
Nationwide Public Records
Search by maiden/spouse name, age, DOB or SSN for unlisted numbers, addresses, roommates and family members.
Say your are trying to locate the actual street address for someone you are investigating. If you know the zipcode +4 number for your subject (check their credit header 
), you can use that info to locate the address range for the street they live on. Once you know that, then you can plug the various addresses into a free phone search engine (try anywho) until you get the phone number of one of the neighbors. Then just call them up and ask for your subject. They will probably tell you that you have the wrong number, etc., but just keep digging until you get a neighbor that loves to talk. No telling what you will find out!!!
Another great address search resource is the voters registration office. Say the person you are doing a
people finder search on is keeping a very low profile by using a PO Box for all their mail and bills. I can
almost guarantee that no matter how careful they are to keep their street address out of address finder
databases, they will always use their correct home address and telephone number with area code on their
registration form. Even losers like to vote!