It's the Motivaider
Basically it is a little thing like a pager you fasten to yours (or your child's belt) and programme to vibrate at certain times.
Very useful for things like reminding someone to visit the toilet (kid) or to make a positive comment (adult) or to initiate eye contact (kid).
You can even wear one at the same time as your child and set them to vibrate simultaneoulsy, so that you know when he gets the 'message' and can note whether he responds accordingly.
We have started using them for toilet training. I think they have huge potential.