MATHEMATICS

http://aaamath.com/

 You can explore a trial version of a CD available through this website (K-8).

http://www.sheppardsoftware.com/math.htm

This site covers the basics through Pre-Algebra.  Fractions are my favorite!

 http://setgame.com/

 Daily puzzle – kids love this.  Also take a look at Quiddler at the same site.

 http://www.learningplanet.com/

A variety of learning resources for math and other content areas.  Interactive games, worksheets and other activities available.  Be sure to play Sudoku on this site and Math Mayhem.  The link to get you there directly is below.

www.jwdotc.com/home/math/default.asp

Timed math facts – can keep track of progress.

nlvm.usu.edu/en/nav/vlibrary.html

Virtual math manipulatives.

SCIENCE

http://dsc.discovery.com/

http://www.billnye.com/

http://chem4kids.com/

This site covers matter, atoms, eleements, reactions, etc. 

MISCELLANEOUS

http://www.factmonster.com/

This is an incredible site with social studies, science, math, geography and more.