(Sample link) White House for Kids http://www.whitehouse.gov/kids/whlife/index.html
Louisiana http://www.50states.com
Fun Brain Http://www.funbrain.com
Macmillan Reading http://treasures.macmillanmh.com/national/students
Base Ten game http://www.learningbox.com/Base10/CatchTen.html
National Geographics for kids http://www.kids.nationalgeographic.com