Miss Maggie Around the World in 80 Seconds

http://www.missmaggie.org/scholastic/roundtheworld_eng_launcher.html

Great site for building speed in mental math. When we discontinued our son from Kumon, we experimented with this site. Worked very well. Our hyperative son loved being able to jump around the room shouting out answers to questions, and seeing how many seconds it took him to finish a round of addition and subtraction questions. We started with this when he was 5. The "game" has two settings - "easy" and "hard". Pros - Fun for children because it takes less time than filling out worksheets. Cons - Great for testing addition, subtraction, multiplication and division facts, and not suitable for teaching and learning those concepts. Most importantly, helps build speed after the concepts have been learned.