Adventure travel
   • Adventure Collection: A group of eco travel operators offering unique journeys all over the world
   • Eco Family Adventures: Family-focused itineraries catering to both parents and kids

National and state parks
   • About.com: Has a national park locator searchable by state, activity, driving distance from major cities, and more
   • Campgrounds-by-city.com: Listings for thousands of state, national and private campgrounds

General resources
   • Sustainable Travel International: Has an eco-destination guide searchable by vacation type and/or region
   • Google: Offers a new map-based service with info about eco-friendly locations in five major U.S. cities
   • RoadsideAmerica.com: A guide to offbeat U.S. tourist attractions (Leila's Hair Museum, anyone?)