It has been discussed before you can put chi machine
in the search box. Also on the Ask Barefot forum it has
come up several times.

I got one a year or so ago, but it is a knock-off I guess of "the real thing." I watched something that was sent to me yesterday by a raw-foodist whose newsletter I subscribed to. Check out this site http://www.chidvd.com/index.php.
These videos are long, but take the time to watch them. They are very intriguing. If mine works, I found out I am not using it enough.

But I suppose if you like to jump, rather than being shook in a figure 8, you would prefer the rebounder. I just tried jumping for a while and I don't think I like it so much.