Another great site with learning games. This one seems to be completely free (I haven't used it a ton, so maybe I just didn't reach the free-use limit). Best of all, it has games for nearly every subject, and the games are categorized by grade and subject.
IXL has hundreds of Math related games, categorized by grade and topic. It is a subscription based site, but allows quite a few free uses, and even once you've used up your free practice for the day it refreshes and let you try again the next day.
IXL is the world's most popular subscription-based learning site for K-12. Used by over 5 million students, IXL provides unlimited practice in more than 4,000 math and English language arts topics. Interactive questions, awards and certificates keep kids motivated as they master skills.
Was having trouble with google reader. I ended up on wikipedia on edublog and this was one of the names referenced so I'm testing out my diigo skills with this one...