We've seen wind turbines attached to skyscrapers and flying like balloons. But until now wind turbines were always part of large, energy projects. You couldn’t attach one to your roof. That's starting to change. Companies like Skystream are making smaller turbines that can reduce or eliminate your electricity bill and provide "quiet, clean electricity in very low winds."

Many states have devised incentives that make having a home wind turbine less costly. Even so, one expert estimates that the turbine would take around 20 years to pay off, in terms of saved electricity costs. So think long-term when you're thinking green, and if your neighbors get mad, remind them that you could be putting in a mini-nuclear reactor instead.

Skystream, via The New York Times