The Swiss ball is pretty cool. There are some workout programs built totally around using it. I had packed mine away sometime last year, but brought it out over the weekend and pumped it back up. My wife and I have both read a number of articles lately that featured the ball and thought it might nice to give it another try.
I'll agree with docta, pumping it up was an exercise routine itself. Of course our one-year-old, Ian, was a great help with that. Of course once the ball was up to size, he knew he had a new toy!
Travis