Math Playground is a mathematics learning site for students in grades K - 6. Practice your math skills, play a logic game and have fun! http://www.mathplayground.com/index.html
Interactive math activities http://www.k111.k12.il.us/king/math.htm
Math Cats - more interactive math. http://www.mathcats.com/explore.html
Change Maker An interactive game working with money http://www.funbrain.com/cashreg/index.html
Tangram Puzzles Developing Geometry Understandings and Spatial Skills through Puzzlelike Problems with Tangram http://standards.nctm.org/document/eexamples/chap4/4.4/index.htm
Hungry Frog Practice math facts in this fast-paced game. Click on "Play now." http://www.hungryfrog.com/