U.S. National Parks Service
Gazetteer related to National Parks and other geospatial data.
ftp://ftp.its.nps.gov/pub/
Intermountain GIS Support Center
Digital orthophotos and scanned images of Petroglyphs National Monument and Pecos National Historic Park. DEM of Salinas Missions.
http://nps.unm.edu/doq.htm
U.S. Geographic Names Server
Downloadable database of over 2 million physical and cultural geographic features.
http://www-nmd.usgs.gov/www/gnis/
Native American Maps
Online GIS of thematic maps related to Native American cultural heritage in the U.S. and Canada.
http://indy4.fdl.cc.mn.us/~isk/maps/mapmenu.html
Urbavista Project - Organization of World Heritage Cities
Future interactive GIS of World Heritage cities, to include Quebec.
http://www.ovpm.org/ovpm/english/urbavis.html
US GeoData
Free USGS maps to download.
http://edcwww.cr.usgs.gov/doc/edchome/ndcdb/ndcdb.html
Cartographic Data Archives
Free digital maps; currently focuses on U.S. maps. Invites anyone to add their data to the website.
http://spectrum.xerox.com/pub/map/www/index/html
Guide to Online & Mostly Free U.S. Geospatial & Attribute Data
As the name says.
http://cast.uark.edu/local/hunt/index.html#BASE
Environmental Systems Research Institute (ESRI)
Free downloadable data set of Washington, DC.
http://www.esri.com
TIGER U.S. Census Database
http://www.census.gov/geo/www/tiger/
Canada NAIS
Interactive online GIS of Canada.
http://ellesmere.ccin.emrca/naismap/naismap.html