Shakti Mat
Breakfast on 1 recently hosted a physiotherapist advertising the Shakti Mat - a yoga mat covered in plastic circles, with each circle consisting of 20 or more sharp spikes. The mat is supposed to work like a bed of nails, activating acupressure points. I've seen the mat sold at shows such as the Go Green Expo, and have stood on one - the points are really sharp, and without socks it was especially painful.