Originally Posted by surfgeek33
I'm not sure if this has gotten adequately answered, but in case not, I'll throw in my 2 cents...
For CA the complete place is atlas.ca.gov, its got everything but its not the most user friendly, and some of the "product" is fairly specific in its intended usage (i.e., for ArcGIS or other GIS packages).
For the rest of the US (and a considerably more user friendly) use the "Maplocator" at usgs.gov :
I'm not sure if the link will work, but if it doesn't go to http://www.usgs.gov
--> "Maps, Imagery, and Publications" --> "Download digital scans of topo maps" --> "Maplocator"
Hope that helps!