Nature is good at dealing with organic garbage: Bacteria turns it into plant food. Rural residents use this phenomenon to generate free fertilizer in compost piles. Rotting trash attracts rodents and repels neighbors, however, so those of us off the farm tend to throw out our organic waste along with everything else. But the NatureMill Automatic Composter ($400; naturemill.com) is like a Mr. Fusion for your garden. The size of a normal trash can, it produces enough compost to sustain up to a 400-square-foot plot, while a charcoal filter scotches any odor. Toss in almost any unwanted edibles, and the machine turns them into a nitrogen-rich soil additive. And the NatureMill is easy on the electric bill, costing about 50 cents a month to operate.