Wristwatches, to a great extent, play a vital role when it comes to making a fashion statement. This is one gadget that has been the in-thing for centuries and is still going strong. My favorite, though presently just a concept, is a tattoo wristwatch. Itâs kind of an electronic tattoo that can function as a wristwatch. Powered by kinetic energy, it uses a wireless signal to sync up with an external timepiece to make sure it is correct. Just hold the wrist facing upwards and see it illuminate.