Eduplace - math help, aligns with our math text http://www.eduplace.com
A Plus Math - a great place for printable flashcards! http://www.aplusmath.com
Some suggestions for book series that might HOOK your kids! Often this is the best way to get reluctant readers excited! They want that next book! http://www.scholastic.com/familymatters/read/gr3_5/bl_series.htm
Google for Kids http://www.google.com/Top/Kids_and_Teens
Funbrain - More math fun and practice! http://www.funbrain.com