If you don't already go to this site in your classroom by now you need to give it a try! http://mrnussbaum.com/
Our students really enjoy the games to help reinforce the math concepts that we teach to our students. The latest thing that we discovered is the fun graphing ideas. They are easy to use and a great introductory skill if you are teaching students how graphing works.
One of our favorites is the cash out game where students learn coin recognition and counting back change.
Check this great site out...games also available on iPads and mobile devices!!