Scholastic http://teacher.scholastic.com/activities/CLF/index.htm
Learning Planet http://www.learningplanet.com/stu/index.asp?tab=0
PBS Kids http://pbskids.org/
Kindersite http://www.kindersite.org/Directory/DirectoryFrame.htm
FunSchool http://funschool.kaboose.com/preschool/index.html
Starfall http://www.starfall.com/
National Geographic Kids http://kids.nationalgeographic.com/kids/