In order to make running laps in phys-ed class easier, Viktor Gordeyev invented gasoline-powered boots. These super-boots are capable of propelling the wearer at upwards of 20 miles per hour. The boots contain miniature pistons which operate as two-stroke engines, firing (hopefully) as the wearer's foot leaves the ground, causing a stronger stride.
Test runners have gotten up to 21.7 miles per hour in the latest versions of the boots, under development in Russia for decades. Some problems exist with the technology -- for one thing, the boots are apparently heavy enough that there is no net energy gain in using them. Even so, we'd like to get our hands on a pair.
Read more about the boots at the New York Times.