The Oswego, New York school district website has a great resource for math teachers called Math Magician Games. The games cover basic addition, subtraction, multiplication, and division problems. The games are appropriate for students up to about the 8th grade.

Application for Educators
The games are straight forward and simple for students to get started using. The games are not flash-based so there is very little concern about whether or not your computers have the latest plug-ins or browser updates. The students can sit down at the computer and get started with very little “down time” as you try to get everyone playing.