Common rubber balls are just no fun. So why not get a Sphero 2.0 Robotic Ball Gaming System?
Compatible with IOS and Android devices, the Sphero Ball can be used with over 25 apps and works like a remote controlled vehicles. It rolls at 7 feet per second, wherever you want it to go and even has two ramps so that you can make the Sphero do stunts.
Normally sold for £99.99, you can get if for £20.00 less at I Want One of Those and pay only £79.99: http://www.iwantoneofthose.com/gift-gadgets/sphero-2.0-robotic-ball-gaming-system/10866378.html