Economist.com
Economic and commercial data on countries around the world from a respected source.
http://www.economist.com/countries/

GEsource World Guide
A handy tool that allows you to select two world countries or regions and compare demographic, geographic and economic data at the press of a button.
http://www.gesource.ac.uk/worldguide/countrycompare.html

Maptown.com
World facts, with the emphasis on economic statistics.
http://www.maptown.com/geos/

PBS - Commanding Heights
Take an in-depth look at the economic development of dozens of countries around the world, or learn more about the growth of globalization and world trade in general.
http://www.pbs.org/wgbh/commandingheights/

Penn World Tables
A mind-boggling array of economic statistics on over 150 countries around the world.
http://datacentre.chass.utoronto.ca/pwt/

The World Bank Group
Economic surveys of countries around the globe.
http://www.worldbank.org/html/extdr/regions.htm

US Census Bureau
American trade statistics.
http://www.census.gov/foreign-trade/www/statistics.html