This site has excellent resources for the math teacher and student. This site has several games for different grade levels.
Games cover addition, subtraction, multiplying, and division.
If it is elementary math, it is on this site. Brain Teasers Change Maker Figure out how many of each bill or coin that you expect to get back when you pay for something. Dave's Math Tables Excellent Math site. In either Spanish or English. This site gives students a problem a week to solve.