Here is a link to a blog post that I wrote awhile back about a math game that the students have learned how to play in class. We have only played it for adding and subtracting but if you have older children you might want to try it with multiplication and division.
www.staceyhernberg.com/home/a-math-game-for-practising-basic-facts
www.staceyhernberg.com/home/a-math-game-for-practising-basic-facts