www.mathcats.com. This website promotes open-ended and playful explorations of important math concepts in the context of online games, interactive applets, and activity suggestions... Unique and diverse online explorations are provided on the website... Student discoveries do not have to stop at the computer; exploring geometry through the hands-on crafts and art activities presented under the Math Crafts section will provide a fun and challenging learning experience as well...
http://www.ricksmath.com/ This site contains more than 4,800 math problems for students pre-kindergarten to high school who need help learning to count, write numbers, understand place value, addition, subtraction, multiplication, division, prime numbers, composite numbers, least common multiples, greatest common factors, factoring whole numbers, fractions and lots more.
http://www.prongo.com/ Prongo.com is an educational website for Kids. In the mood for a fun collection of games that might just teach you something at the same time? Practice your math skills in games like Lemonade Larry and Batter's Up Baseball. Also includes age-specific games like checkers, connect the dots, matching, word and maze games. Prongo.com also offers Quizstation which allows you to create online quizzes.
http://mathplayground.com/index.html Welcome to Math Playground, an action-packed site for elementary and middle school students. Practice your math skills, play a logic game and have some fun! The primary goals of Math Playground are to help students feel more confident about their math skills and to help them form more positive attitudes toward the subject of math.