Homework Spot A great site that has homework assistance, educational puzzles, useful articles, etc.
Kids Connect A comprehensive site with links to every subject imaginable
Discovery Education Help with Math addition, subtraction, division and multiplication, plus explores various topics in science, english and social studies
A+ Math Online math games and flashcards
Fun Brain A popular site with kids, has interactive arcade-style educational games
Kidipede Ancient Roman, Greek, Chinese, and Egyptian history for 6th graders
Fossils for Kids Lots of fossil information