In the late Nineties, an Australian company called Metal Storm used digital technology to invent a gun that can fire a million rounds a minute, spitting out bullets so fast they literally push one another through the air, increasing overall acceleration. A test firing of 36 barrels tied together turned a series of 15 doors into splinters in 0.2 seconds. DARPA has spent at least three years and more than $10 million investigating the technology's battlefield potential. Meanwhile, at Sandia National Laboratories in Albuquerque, DARPA-funded scientists are working on land mines that can jump around like giant, lethal checkers. If one blows, another comes bounding over to take its place. Each mine contains enough juice for 100 leaps.