When you're cutting wood with a power jigsaw, sometimes the up-down motion of the fast-moving blade becomes so blurry that you start to lose sight of the line you're trying to cut. I never considered this a solveable problem, which is probably why I don't work at Festool.
Festool's super-engineers have added a "Stroboscopic LED"—essentially a strobe light—to the front of their Carvex jigsaw. The light is timed with the motion of the blade, freeze-framing it in the same position at each cycle, so once you get going it looks like the blade's not moving at all:
Nuts, right? Don't get too excited if you're in North America; while the Carvex is available in Europe, Festool has just announced they won't be bringing it to U.S. or Canadian shores anytime soon.