This is a fellow teacher's bog. She posts a lot of great sites that you can go to to find fun interactive games that students can do either on the SMARTboard, on individual computers, or in small groups!
I read about this site in one of my education magazines. It has online textbooks that you can use for free. You can also "make" your own textbooks that fit better into your classroom! I haven't been able to play around with it too much, but it's worth a try!