http://saxonpublishers.hmhco.com/en/saxonpublishers.htm        (Math/Phonics) 

http://www.sfsocialstudies.com/     (Social Studies)

http://www.eduplace.com/    

http://www.billybear4kids.com/

http://www.pbs.org/

http://dsc.discovery.com/

http://www.50states.com/

http://www.starfall.com/

http://www.spellingcity.com/     (Spelling practice)

 www.learninggamesforkids.com