http://itunes.apple.com/us/app/motion-math-hd/id410521340?mt=8 motion math in hd - depending on where your kiddo is math-

http://itunes.apple.com/us/app/words-with-friends-free/id321916506?mt=8 words with friends - there is a pass and play option that I use to play with my son on one device, and my older son and I play each other through our iPads.

Garage band also has an app if they like to create music.

~Lisa
http://www.lisaabeyta.wordpress.com/