I have one called the 'BSLIMMER Vibration Plate', although I didn't buy it to lose weight. I use it only occasionally - on those days when my muscles ache - but I find it really relaxing, especially when combined with breathing, stretches and weights.
It seems to remind the brain where the muscles are and 'jiggles' them awake, if you know what I mean. I wouldn't use it instead of regular exercise but, combined with it, I find the machine really beneficial.
Another useful gadget is a simple back stretcher, which arches the back to enable a good spine stretch. Either of these devices would be useful for anyone but are, in my opinion, especially good for Parkies as they improve flexibility.