Talk about going full circle. A garbage truck running on methane picks up the trash out in front of your home and deposits it in a landfill. Over the next few years, that garbage begins to deteriorate, releasing methane gas in the process. That methane waste gas is captured and re-used by the same garbage trucks to pick up your trash. While we aren't necessarily proponents for landfills, at least some good can come out of their creation. Methane gas is a pretty horrible greenhouse gas, so it's much better to capture it in some way than to let it out into our atmosphere. When burned, however, methane (natural gas) releases more energy and less carbon back into the atmosphere that other, more traditional hydrocarbons ... like petroleum-based gasoline. T. Boone Picken's company Clean Energy Fuels has recently made an acquisition for this purpose in Texas.
Another use for the waste-methane emitted from toxic dumps is for electricity generation. Many landfills pipe their natural gas to power-generating facilities where huge turbines could potentially create the power for your next electric car.
[Source: Automotive News - sub. req'd]