Galileo
Use the K-12 links; password required for home use and may be obtained from your school media specialist.
http://galfe1.gsu.edu/cgi-bin/homepage.cgi?style=&_id=a80aa83d-1283633098-5048&_cc=1
Merriam-Webster Online
Dictionary, thesaurus; word games; learner's word of the day; daily podcasts
http://www.meriamwebster.com/
The Library of Congress
America Memory
http://www.loc.gov/index.html
World Book Online
Research
http://www.worldbookonline.com/wb/Home