US Gov't resources

Atlas of the US
Social Explorer
US Census Bureau
US Census Bureau American FactFinder2
USGS/BGN Geographic Names site
Statistical Abstract of the U.S. (After more than 130 years of publication, this compendium was discontinued in 2011, a glaring disservice to both the ideal of an informed citizenry in a democracy and to students of the United States. An MA thesis on why this happened would be interesting and worthwhile.)
USGS Tapestry of Time and Terrain
USDA - National Agricultural Statistics Service (NASS)
USDA - GMU CropScape
NASS Quick Stats

Canadian Gov't Resources

Statistics Canada

Mexican Gov't Resources

INEGI
www.what.mx

Other resourses

Google Earth

Degree Confluence Project: Photographs taken at integer latitude, longitude positions

Sperling's Best Places gives a quick way to look up overview characteristics of places by name or by zipcode.

Place Blogger

TerraServer-USA

The Gateway to Astronaut Photography --- NASA Crew Earth Observations. The "Find Photos" and "Image Quiz" links are especially cool, ...er... useful!

Historical Atlas of the US. University of Richmond.

Mapping the Nation: History and Cartography in 19th Century America website

Some topical web-bits