Here's an article on an open source map project. It looks like a viable source of maps to me. My urban AO is already finished and seems to be accurate. Although I would refine the detail of landmarks if could.
http://www.networkworld.com/communi...-side?source=NWWNLE_nlt_linux_2010-07-14

http://wiki.openstreetmap.org/wiki/WikiProject_United_States

And the 3per's blog was just discussing this.
http://sipseystreetirregulars.blogspot.com/2010/07/praxis-maps.html

"I come in peace. I didn't bring artillery. But I'm pleading with you, with tears in my eyes: If you fuck with me, I'll kill you all." Marine General James "Mad Dog" Mattis