Online Math Games

Aunty Math
K-5 daily activities
http://www.dupagechildrensmuseum.org/aunty/index.html

Cool Math
http://www.coolmath.com/

Fun Mathematics
http://math.rice.edu/~lanius/Lessons/

I know that
There is a free registration and you can play the games for free you have to dig around till you get it though! All I did was tried to play a game and it walked me through the free registration.
http://www.iknowthat.com

Internet4Classrooms link list for lots of online math games
Kindergarten Mathematics Skills, Algebra, Geometry, Measurement, Data Analysis and Probability
http://www.internet4classrooms.com/skills_k_math.htm

Kids Numbers also has Worksheets
http://www.kidsnumbers.com/

Math is Fun
http://www.mathsisfun.com/

Multiplication Games – You can play games for individual facts or for a group of facts.
http://multiplication.com/interactive_games.htm

Nim Number Game
Nim is a game of logic and strategy. The goal of Nim is to be the player who removes the last of ten protons from the computer screen. A player must remove one or two protons during their turn. The player who removes the last proton wins.
http://education.jlab.org/nim/index.html

Online math games for kids
http://www.scweb4free.com/

Play Kids Games
http://www.playkidsgames.com/mathGames.htm

Rainforest maths
Over 800 interactive mathematics activities for Kindergarten to Year 6 covering the math strands of Number, Number Systems, Operations & Calculations, Strategies & Processes, Patterns & Algebra, Measurement, Space & Geometry, Chance & Probability, Data Analysis and Money.
http://www.rainforestmaths.com/

Woodlands Maths Zone
Several fun online interactive activities here to help you not only improve your mental maths skills, but also to help you with your SATs Revision. These pages are aimed at 7 -11 year olds.
http://www.woodlands-junior.kent.sch.uk/maths/