Math Magician http://www.oswego.org/ocsd-web/games/mathmagician/mathsmulti.html
Meteor Multiplication Game http://www.arcademicskillbuilders.com/games/meteor/meteor.html
Grand Prix Multiplication Game http://www.arcademicskillbuilders.com/games/grand_prix/grand_prix.html
Gamequarium - Tons of math games http://www.gamequarium.com.