Geography

United States

General

Elevations and Distances in the United States -- Geological Survey
Encyclopedia Smithsonian: Geography
EROS Image Gallery -- Geological Survey
Geographic Names -- Geological Survey
National Parks
Smithsonian Magazine
State of the Land -- Department of Agriculture
U.S. Gazetteer -- Census Bureau
Wild and Scenic Rivers

Maps

Geodata.gov - Federal, State & Local Geographic Data
National Atlas of the United States
The National Map -- Geological Survey
State of the Land -- Department of Agriculture
Topographic Maps
          Topographic Map Symbols
Mapping and Cartographic Resources -- Census Bureau
          TIGER Map Server Browser
USGS Global Change Fact Sheets

Statistics

American FactFinder -- Census Bureau
Census Bureau Geography -- Census Bureau
Economy at a Glance -- Bureau of Labor Statistics
MapStats
Social Statistics Briefing Room: Demographic -- White House
State and County Demographic and Economic Profiles -- Census Bureau
State of the Land -- Department of Agriculture
Statistical Abstract of the United States -- Census Bureau

World

General

Background Notes (by country)
Country Studies -- Library of Congress
Economic and Social Development -- United Nations
UNESCO
USAID Regions and Countries
World Factbook -- CIA

Maps

Geography and Maps: An Illustrated Guide -- Library of  Congress
Historical Map and Chart Collection -- NOAA
Maps and Geographic Information Resources -- United Nations
Map Collections: 1544-1999 -- Library of Congress
World Factbook: Reference Maps -- CIA

Statistics

Economic and Social Development -- United Nations

GIS

Geographic Information Systems -- Geological Survey
          Clearinghouse Web Links