iphone with earthWondering what brand of toothpaste is the most eco-friendly? There’s an app for that.

Need to know which species of fish on the menu were caught sustainably? There’s an app for that.

Long to plant a tree with every swish of your PhoneSaber? There’s not an app for that … yet. But check out the apps that plant trees — digital and otherwise — that are already available.

Contrary to the rest of the going-green retail world, iTunes doesn’t have a “green” category in its app store (For better? For worse? Can’t decide….). And search for “green” in the iTunes store and the first app that appears is “BreakMeter — the Golf Green Reader.” Hmmm … that’s not quite what I meant.

Fear not this categorical inconvenience, dear Grist reader, we have examined the 50+ carbon calculators, shopping guides, mileage trackers, and more of the green iPhone world and offer some recommendations on where to best spend your App store dollars.

How our guide to green iPhone apps works:

Shopping

3rdWhaleMobile3rdWhale Mobile: This app uses GPS to find green restaurants, stores, and travel destinations in 100 cities in the U.S. and Canada, and displays results on a map with directions.   No iPhone? 3rd whale is working on Android and Blackberry phones. Free 2 stars iTunes

GoodGuideGoodGuide: Use this app to find out what’s in 75,000 common household products. No iPhone? Check out goodguide.com. Free 2.5 stars iTunes

Go Organic!Go Organic!: This app finds organic grocery stores and Earth Day events near you. Free 1.5 stars iTunes

Gorgeously Green Survival GuideGorgeously Green Survival Guide: Want to know the dirt on your makeup before you buy it? This app suggests chemicals to avoid in makeup and sunscreens and gives tips on food and product labels. $0.99 5 stars iTunes

greenopiaGreenopia: This Los Angeles-specific app boasts 1,000+ searchable and map-able listings of green businesses, restaurants and services. More U.S. cities to come later in 2009. Free 4 stars iTunes

Greenpeace Tissue GuideGreenpeace Tissue Guide: Research brands of consumer paper products to find the greenest tissues, paper towels, and toilet paper. Free 3.5 stars iTunes

shopgreenshopgreen: This app is more than just a shopping tool. Enter information about your green habits and the app will connect that information with promotions from local businesses. No iPhone? shopgreen is available on other mobile platforms. $0.99 2.5 stars iTunes

If you can only download one: Get the GoodGuide.  Reviewers praise the level of detail in the GoodGuide database as well as its ease of use.

Shopping, Food, Transportation, Energy Monitoring, Recycling, Business and Activism, Entertainment, News, and Green Living Tips.