I have a simple version of these at home, just a seat-shaped cushion thingy that sits over the couch which has a vibrate and massage setting which DH bought me... probably in the hope it would get him out of too many demands for a shoulder rub!

I've chosen not to use it during pregnancy as I'm concerned about the level of electro-magnetic radiation. Although everything electronic (yr TV, phone, alarm clock etc) is putting out this energy, I just figure it's not great in larger doses so close to bubs. I've heard that you should never sleep on an electric blanket switched on for the same reason (pg or not).

I'm sure it's fine in small doses but worth considering.