The following websites provide great opportunities for students to play games on the computer while enhancing their math skills!
http://www.mathplayground.com/
Games of varying levels that provide help with math basics. All students can benefit from math
basics practice!
http://www.coolmath.com/
Another site of games that are entertaining but also give students the opportunity to work on math skills.
http://www.ixl.com/
This site is fantastic. Students don't have to work at their own grade level, but can if they choose to do so. I have used this site with several classes successfully in the past.
http://calculationnation.nctm.org/
This site requires you to join as a user, but provides opportunities to compete against other math students to be the best in the Calculation Nation!