1. FactMonster.com The website is organized by the following topics: World & News, U.S., People, Wordwise, Science, Math & Money and Sports. Check out the timelines for both World and U.S. History key facts and famous people.
2. Convert-Me.com Need help converting measurements? This website provides conversion tables for standard U.S. and metric measurements as well as conversions that are no longer used like the measurements used in Ancient Roman times.
3. The World Factbook This website is maintained by the Central Intelligence Agency (CIA) and is updated frequently to reflect the changes that happen throughout the world. You can find information for more than 260 countries worldwide, including their history, people, economics, military and area maps.
4. Biography.com Biographies of the famous and noteworthy, past and present are available. Check out Bio’s Best for biographies of all U.S. Presidents as well as women in history.
5. MSN Encarta Encarta offers an online encyclopedia, an atlas, a dictionary and thesaurus, and a special section for homework help for grades K-12.
6. Gallup.com Gallup Polls are famous for providing statistics on the opinions of both Americans and the world at-large. Topics include politics, economics, healthcare, military and transportation.
7. InfoPlease.com This is the “big brother” website of FactMonster.com and includes a broader database of subjects that are applicable in general to ages 11-Adult. Topics include: Astronomy, Sports, Arts & Entertainment, World History Timelines, and even a perpetual calendar with a cross-reference to Hebrew, Chinese and Islamic calendars.
8. Wikipedia: Reference Desk Wikipedia is probably the most well-known of all the online research and encyclopedia sites. For homework help, the reference desk is the best place to start for researching a particular topic. Unlike Wikipedia’s main page, the Reference Desk is organized into the following topics: Computers & IT, Science, Mathematics, Humanities, Language, Entertainment and Miscellaneous.
9. SparkNotes.com SparkNotes has an impressive collection of study guides for many of the subjects covered in grades 8-12. Check out their No Fear Shakespeare section, which puts a modern-day translation to many of Shakespeare’s works side-by-side the original for easier comprehension.
10. CliffsNotes.com The website has even more titles and topics than the popular yellow-cover study guides that have been in print for decades, and made Cliffs Notes a household name. Free study guides and articles are organized by the following topics: Literature, Writing, Foreign Languages, Math, Sciences and Test Prep.
This list is from Yahoo!