ABCya! Go there now! :)
ABCya! is a site with educational games and activities for elementary students. All their activities were created or approved by certified teachers. The games are FREE and some would be great for use with a SmartBoard.
Trust me, this site is worth checking out! Just make sure you have some time because there is so much there! Your students will LOVE it! It would also be a great site to share with parents to use for reinforcement for their children while at home.