Even in this age of pervasive cell phones and GPS systems, it's possible to get lost. And not lost like "do I take a left or a right to get to Denny's," but the kind of lost where if you don't get found, you're likely to die of exposure and/or be eaten by a bear. This little piece of fabric could put your mind at ease, enabling rescue anywhere on Earth.
Hardcore adventurer types sometime carry around personal locator beacons, which are electronic gadgets that (in the event of an emergency) can send distress signals to a constellation of 11 satellites, which will automatically alert rescuers with a precise location. The problem with such beacons is that they're entirely useless if you don't HAVE one, and unless you anticipate getting lost (which is kind of a contradiction in terms), you're not very likely to bring one along with you. They're also expensive and relatively fragile electronics, and don't respond well to the type of abuse that comes with (say) unwillingly abandoning your ship in the middle of the ocean.
The European Space Agency has taken the most important part of a personal locator device, the antenna, and de-electronized it into a small, lightweight, waterproof, and flexible patch that looks and feels like a square of fabric. When combined with some kind of user-activated power system (anything from a chemical battery to a solar cell), the result is an extremely durable emergency locator system that can be integrated directly into life preservers, wetsuits, or even jackets. It's zero maintenance and acts and feels like a part of your clothes, and you probably won't even notice that it's there until you find yourself not being able to find yourself in the next mega mall, parking garage, or corn maze.