I have some who use balls some who don't - personally I prefer not to use them I like to see them explore the spare bed and the corners of the room. Playing with the Puzzle playground and climbing my huge teddy bear (over 4 feet tall) but then I know not everyone has the luxury of a hamster specific room and I would rather they use a ball and give their hamster some out time than live in a cage 24/7. There is an article on zoomer balls which you all may find interesting at Hamster Central - especially as it was written by me
