Check out some of these sites to build and devlop new math skills!

pizza

Pizza Party: Fun games using pizza to teach fractions!

baseball
Math Baseball: A fun way to learn math facts. Can be a 1 or 2 player game.

logo

Skill Builders: Has great games according to grade level and topic. User can switch to work on a different grade level.
Cool Math For Kids: Many sites for exploration and math art.
Auntie Math: Are you good at finding patterns? Check out this site for a new word problem every other week.

Math Games: Covers a variety of topics. Can adjust to all grade levlels.