The iPhone's amazing touchscreen and accelerometer based technology has revolutionized the way we use our phones, and programmers have created some amazing applications that take full advantage of the capabilities of the phone to change our lives in positive ways. Take the GreenMeter app for example... this app is designed to help you adjust your driving habits in order to reduce CO2 emissions and save you money on gas. The app uses the iPhone's accelerometer to measure forward acceleration, compute engine power, fuel economy, fuel cost, carbon footprint, and oil consumption. Just take a look at all the data on the app and see how adjusting your driving style changes the visual graphs for the better and worse. If you use the GreenMeter right, you can become a more environmentally friendly driver and save yourself some big money on gas. Greenmeter costs $5.99 to download, but since that's just a little more than the cost of a gallon of gas, it's well worth the small investment. I'm Elizabeth Chambers. ...