We love finding old abandoned ghost towns. We use various books on Ghost Towns to locate our targets which range from towns like Oatman, AZ, where the ghosts are actually tourists (or wild donkeys),

and Jerome, AZ

to real ghost towns where you need help, like DeLorme's Street Atlas and their glopal positioning system to locate the Ghost Towns.
Helvetia, AZ Sasco, AZ
And there were a couple that we would not have found without the GPS - for example, Cerro Colorado where we had to drive up a dry creek bed to find the ruins.