As part of the Georgia Virtual Vault, the GA Secretary of State's office has put historic Georgia Maps online. There are maps of 161 GA counties (some no longer in existence) that date from 1866-1935. You can browse a list of maps, or search the database in categories such as title, publisher, year, notes, etc.
The maps are available in high resolution and individuals can use the maps themselves as long as they give credit. For each map, there is a usually a bit of information about it's creation.