The Top Eco-Friendly Smartphone Apps

Wondering what kind of light bulb to put where? Concerned about how inefficient lamps contribute to your electric bill (and to global climate change)? Not sure where to find energy-efficient light bulbs? Light Bulb Finder to the rescue. This app -- named one of the best green apps by the EPA -- lets users determine cost savings gained by switching to more efficient light bulbs ​and even helps users buy new light bulbs directly from the app. For Android and iPhone.

Shopping is confusing enough when there are 318 different brands of toothpaste on the shelf; adding green credentials into the mix only makes things more baffling. But wait -- what if there were a green app that lets you scan a barcode, then informs you about that product's environmental footprint? It's called GoodGuide, and it takes green shopping to a whole new level, empowering consumers by giving them the dirt on who's really green and who's just greenwashing. Android and iPhone versions available.

There's not much interaction on A Real Tree: This green app doesn't balance your checkbook or warn you when the boss is approaching your cubicle. What it does accomplish, however, is undeniably green. Each time someone purchases the app for 99 cents, the donation pays for the planting of a real tree (thus the name). Through this app's support, thousands of trees have already been planted by groups like Trees for the Future and the United Nations' Billion Tree Campaign. Available from the iTunes App Store.

Should I order the halibut or the tuna? Is eel sushi sustainable? And where can I buy wild salmon? With the green app Seafood Watch, from the world-renowned Monterey Bay Aquarium, it's easy to make smart seafood choices. This green app's interactive features also let you share the locations of good, sustainable seafood restaurants and shops. Available for Android and iPhone.

Anyone who's ever used Earth911 for recycling or other eco-information knows what a great resource it is. Now you can get their info on the go, with their green app called iRecycle. Just let the app know where you want to recycle -- or use your current location -- and iRecycle will tell you what resources are nearby, their hours of operation and driving directions. The app even lets you review the latest in recycling news and tips. Available for iOS, iPad, and Android.

How efficient is your driving? Is your car as fuel-efficient as it could be? Find the answers to these questions with greenMeter, a popular green app for commuters and other drivers. The app provides info on fuel consumption in real time, so you can see just how wasteful it is, for example, to quickly accelerate from a red light. Analyzing your MPG over time can also provide feedback on your car's fuel efficiency, letting you know when it's time for a tuneup. Available for iPhone and iPod Touch.