I had never heard about Speed Stacking - until this morning, when it got a mention on Countrywide on Radio 1 this morning. Some lucky kid had qualified to go to the Speed Stacking World Championships in Denver Colorado, but it wasn't clear to me how it worked, until the child mentioned YouTube, and up I was in a flash, to get my iPod Touch and check it out.
Well, have a look yourself: http://www.youtube.com/watch?v=LyU5v0ZYMjI
Apparently, some PE teachers get the kids to do speed stacking during their PE hour if the weather is too bad for kicking a ball outdoors. If I was a parent, I don't think I'd be very happy with that - maybe good for eye to hand coordination, but not great aerobic exercise!