How about a PowerPoint game? I LOVE using PowerPoint Games. The kids think it's fun, there's no prep at all for me, and we get to practice the skills in a different way.
My kids love playing "I have who has". We try to beat our fastest time when we play.
Rounding...Oh the headaches that rounding causes! My students need LOTS of practice.
4 Corners games are great to get students out of their seats while practicing skills.