(Sample link) White House for Kids http://www.whitehouse.gov/kids/whlife/index.html
(Sample link) National Geographic for Kids http://www.nationalgeographic.com/kids/
Math games http://www.funbrain.com
Reading http://www.starfall.com
Reading, math, and spelling http://www.playtolearn.com
Reading, math, and spelling http://www.kidport.com
Math http://www.coolmath4kids.com