U.S Geological Survey (USGS) 
U.S. Census Bureau
U.S. Fish & Wildlife Service
U.S. Environmental Protection Agency (EPA)
Contra Costa County

Associations
Bay Area Automated Mapping Association (BAAMA)
Urban and Regional Information Systems Association (URISA)
Association of American Geographers (AAG)

Resources 
National Center for Geographic Information & Analysis
Federal Geographic Data Committee (FGDC)
Geospatial Innovation Facility (GIF)
GeoData
GeoCommunity
TerraServer
 
Locational Services 
Google Maps 
Bing Maps
Yahoo Maps
MapQuest