Wildwood Library - find AR books! http://www.wildwoodlibrary.com
(Sample link) National Geographic for Kids http://www.nationalgeographic.com/kids/
Funbrain http://www.funbrain.com/math/index.html
Brainormous Math Games http://www.brainormous.com/
Batter's Up Baseball http://www.prongo.com/math/multiplication.html
Multi Math Skills http://www.elcerritowire.com/4/geometry.htm
Puzzlemaker - Click on criss cross to make crossword puzzles http://puzzlemaker.discoveryeducation.com/