http://www.coolmath4kids.com/
www.yahooligans.com
www.funbrain.com
Social Studies:
http://www.kids.gov/
http://www.kidsknowit.com/
http://www.socialstudiesforkids.com/funfacts/funfacts.htm
http://www.state.nj.us/state/historykids/NJHistoryKids.htm
http://www.wally.org/links.htm
Science:
http://kids.yahoo.com/science
Spelling:
http://www.kidsspell.com/