Not so long ago I was skiiing down a slope in France, wearing a pair of ski goggles which, when I looked down and to my right, showed me my precise location, how fast I was going, where the ski run went (useful in a whiteout). It also told me if I had a phone call and, via a wrist-worn ski-glove-friendly control, allowed me to switch between answering calls or changing the music on my headphones.