This stuff is pure awesome.
My wife got me some of this as a joke for my birthday last year because she knows that I am a geek who loves this dorky kinda stuff, but the joke was on her, as this turned out to be my favourite gift.
It bounces. Its magnetic. It can relieve an enormous amount of stress, so I keep some on my desk at work, and some at home as well. The kids love it just as much as I do!