http://kids.nationalgeographic.com/
Go here for games, blogs from kids all over the world, cool facts and photos of animals and all sorts of fun things to do. 

http://www.starfall.com
Starfall is great site full of games for the beginning reader.

http://pbskids.org/
Find games and activities with all your favorite characters from PBS -- Elmo, Martha Speaks, Arthur and more.

 http://www.luciboo.com/
Luciboo has links to great sites, homework help and games. Luciboo also offers the Firefly browser.

http://www.kids.gov/
This is a great site for finding stuff you won't find anywhere else. Check out the Geospatial Intelligence Kids Agency. This is also a great place to go to find facts about any of the 50 states.

http://www.loc.gov/families/
From the Library of Congress, this site is full of information and fun for kids and parents alike.

http://www.brainpop.com/
Find games and information on everything from the arts to the sciences to health and technology.

http://www.ala.org/gwstemplate.cfm?section=greatwebsites&template=/cfapps/gws/default.cfm
This page is put together by the American Library Association and is a portal to some of the best sites for kids on the web.

http://www.libertyskids.com/
Associated with PBS, this is the website for the program Liberty's Kids. It has games, activities and biographies from the show.