Romantic fool that I am, these were Andy's Christmas present!
He has preferred running barefoot for a while, as it puts much less stress on your joints, but of course unless you spend most of your time barefoot, its hard to develop tough enough feet to cope comfortably with flints, thistles and gritty roads.
Meanwhile, Sarah B had been looking at barefoot alternatives for a while, because of her bad back and had found these "shoes" - Vibram Fivefingers, as she's documented on her website!
They solve the problem for those of us who don't go barefoot all the time by providing an instant sole callous. Although proprioception is reduced, its much better than normal shoes or trainers, and you have a sensitive yet flexible sole which protects you from the discomfort of small sharp stones, thorns or thistles but gives you most of the benefits of being barefoot.
They look a bit mad, but thats half the fun, and they have a fascinating effect on your posture and movement - so much so that you have to break yourself into wearing them gradually to give your muscles and tendons time to adapt!