If you somehow have the occasion to receive one of these, there are apparently some fun things you can use them for, since they are so low power. (INSTEAD of ordering from amazon) See v=http://hackaday.com/2015/08/10/hacking-the-amazon-dash-button-to-record-whatever-you-want/
I would get one with the rebate, except for the face that we buy literally none of the products amazon has buttons for... and we don't have prime... and I don't actually have a use for one right now. But they are kinda nifty as far as hardware goes!