World Almanac for Kids Online http://www.worldalmanacforkids.com/
CIA World Factbook (countries) http://www.odci.gov/cia/publications/factbook/
Merriam-Webster Online Language Center http://www.m-w.com/netdict.htm
Fact Monster http://www.factmonster.com/
Reference Desk (extensive and comprehensive source information) http://www.refdesk.com/
Time for Kids http://www.timeforkids.com
Enchanted Learning http://members.enchantedlearning.com/
Liberty's Kids http://www.libertyskids.com/
Ben's Guide to Government for Kids http://bensguide.gpo.gov/
The Internet Picture Dictionary (English & other languages) http://www.pdictionary.com/