National Library of Virtual Manipulatives http://nlvm.usu.edu/en/nav/vlibrary.html
Interactive Math http://www.shodor.org/interactivate/
http://www.schooltimegames.com/Mathematics.html
Iknowthat, is a multi-subject, mostly lower skills website http://www.iknowthat.com/com/L3?Area=L2_Math
http://www.mathsnet.net/puzzles.html
This site has millions of SUDOKU puzzles with different levels of difficulty http://www.websudoku.com/
http://jc-schools.net/tutorials/interact-math.htm
http://www.mathplayground.com/games.html
http://www.gamequarium.com/fractions.html
http://www.prongo.com/math/baseball_multiply.swf
http://www.funbrain.com/penguin/index.html
http://www.funbrain.com/brain/MathBrain/MathBrain.html
http://www.eduplace.com/kids/mw/swfs/mathlingo_grade6.html
Solve the riddles to get to the next challenge!! http://www.learningwave.com/abmath/absurd4/index.htm
Magic square games (Comparable to sudoku) http://www.allmath.com/magicsquare.php
http://www.coolmath4kids.com/
http://www.coolmath.com/math-practice-problems.html
http://www.cut-the-knot.org/games.shtml
https://www.pearsonsuccessnet.com/snpapp/login/login.jsp
http://www.brainpop.com/math/
http://www.arcademicskillbuilders.com/