I saw those at Bed, Bath and Beyond. There were some displayed for people to try. Believe it or not, I picked one up and looked for the switch to turn it on! It's quite a bit of effort to make them shake, but you could also work out with weights or other upper arm exercises. But sometimes it helps to have something new to keep us going.

Later....saw them on Ellen and everyone in the audience got one (or a set, I don't know). Anyway, Ellen likes them and said her arms were sore from doing it.

We just had our Christmas party at work and we played 'White Elephant'.. Somebody bought one of these. It's kind of like our new office toy. I used it twice today, but honestly, I didn't feel like I gained much from it. However, a couple of my coworkers love it and have already bought a couple for their house.