The book
@AZ WANDERING BEAR mentioned is called "Arizona Ghost Towns and Mining Camps", and I second the recommendation. It includes GPS coordinates, maps, photos, and bits of history about each site.
I'll also second the recommendation for Ruby, AZ. Check the website before you go, as they are only open 4 days a week (
http://rubyaz.com/), You pay the caretaker $15/adult and he'll give you a map and a little sheet of history about the area, then you are free to explore the whole place as much as you want. I believe for something like $8/night you can camp on-site as well, but bring your own water (and the bathrooms are latrines).
There's also a great little ghost town east of Tombstone called Fairbank that has a great nature hike along the San Pedro River and lots of shade. I've seen people camping there, but it's always been boy scouts, so I'm not sure if it's just coincidence or if it's scouts only camping.
There's also the Ghost Town Trail which takes you from Pearce, AZ through the ruins of Courtland, over to Gleeson - where there's a great curated museum at the restored jailhouse, maintained by Joe Bono, who grew up in the town and whose father ran the general store while the city was still alive. The Ghost Town Trail ends in Tombstone, AZ. Note that the Gleeson Jail (museum) is open on the first Saturday of the month, although we rolled up randomly one day and Jon noticed us poking around from a distance and drove over to let us in. I bet if you gave him a ring to let him know of your timing he'd happily let you in by appointment. The museum is free, but there is a donation box that we always toss some money into. Jon is sure to provide enough history and stories to make it worth your donation.
http://www.gleesonarizona.com/