The Vatican is encouraging travelers to consider the environment when they travel.
ecotravel
Vatican Says 'Travel Green'
Sustain a place: good choices, anywhere, anytime. Saving the world, one community at a time.
A new idea has emerged in Sustain A Place: a user-generated, global database of sustainable choices. Any user can now enter their location and add sustainable choices for both local residents and visitors alike. With one current and comprehensive source, any eco-minded traveler or community member can contribute choices that make the world a better place. Good choices, anywhere, anytime.
Orbitz and Expedia Offer Eco-Friendly Hotels | Eco Travel Logue
Conservation tourism saves sea turtles


12 Tips for Ecotravelers
Great guide on how to help the planet while you travel. Find out where to look for green accommodations, figure out what types of souvenirs to buy, and even where to buy food or rent a car.
Top 10 Places most likely to disappear: An Inconvenient Global Warming Tour
10 places that are likely to disappear because of global warming. Visit them now.
EcoTravel-Asia
A hand picked directory of legitimate ecotourism and environmental resources in Asia. Organized by country. These are not paid listings from what I can see. Same people who do the EcoTourism launchpad. Small but good (and growing).
Ecotourism Launchpad
This is a specialized search engine which focuses on ecotourism resources. It's built with Google technology and is fast and accurate.

Canada National Park Shows How to Persevere Even with Pressure from Developers
I think the approach is great. If a national park can do this, why cannot local communities?
Go Before It’s Gone: Destinations in Peril
5 exotic destinations that may not be around too much longer due to environmental destruction