Watch an incredible demonstration of Slinky tricks


And yet I can barely get mine to walk down the stairs. (KumaFilms via Kottke)


And if you're not hip to the fantastic story of the Slinky's invention:

In 1943, Richard James, a naval mechanical engineer stationed at the William Cramp and Sons shipyards in Philadelphia, was developing springs that could support and stabilize sensitive instruments aboard ships in rough seas. James accidentally knocked one of the springs from a shelf, and watched as the spring "stepped" in a series of arcs to a stack of books, to a tabletop, and to the floor, where it re-coiled itself and stood upright. James's wife Betty later recalled, "He came home and said, 'I think if I got the right property of steel and the right tension; I could make it walk.'" James experimented with different types of steel wire over the next year, and finally found a spring that would walk. Betty was dubious at first, but changed her mind after the toy was fine-tuned and neighborhood children expressed an excited interest in it. She dubbed the toy Slinky (meaning "sleek and graceful"), after finding the word in a dictionary, and deciding that the word aptly described the sound of a metal spring expanding and collapsing.

(Wikipedia)