Undergound Houses

Just some more ideas. http://www.undergroundhousing.com/structures.html

Cohousing

Cohousing seems to be on the rise, notably in Colorado and California.  The Cohousing Association of America has an interesting website along with a directory of cohousing communities in the country (there are two listed in Georgia).  Along with their cohousing communities, Boulder, Colorado (with their progressive local government) has a project for certain housing to be "permanently affordable."