Nothing beats mowing the yard while relaxing in a hammock with a beer and the paper - good thing LawnBott shears up to 30,000 square feet of grass all by itself. The sensor causes a directional shift whenever the mini mower bumps into an object at least 4 inches high or detects a perimeter wire you've laid out. When the rechargeable lithium batteries start to run down, the little guy returns to its docking station to juice up. And it uses only about $10 worth of electricity a year, so even the greenest gardeners have zero reason to stress. The bot can be programmed to a regular schedule, and it's so quiet you can set it to mow at the crack of dawn while you sleep in.