Hoverboards. ('real' ones - not those neck-breaking segways without handles...) Tony Hawks on a not quite hoverboard: https://www.youtube.com/watch?v=HSheVhmcYLA Technology demonstration of superconductor levitation by the Royal Institution: https://www.youtube.com/watch?v=zPqEEZa2Gis And the current crown goes to... Lexus, of all people! They pretty much combined the two. https://www.youtube.com/watch?v=bvYUq6Ox0Hc So... it exists, but still not yet in a practical form, and we've blown way past 2015...