The United States Environmental Protection Agency. EPA's Web site is enormous, and can be intimidating to navigate for newcomers! This page is one of the best on EPA's site for topics associated with transportation and air quality.
The Rocky Mountain Institute. A think-tank founded in 1982 by resource analysts Hunter and Amory Lovins, RMI is one of the best places to find ground-breaking, conservation oriented research activities and information.
The Energy Information Administration. EIA is the statistical branch of the U.S. Department of Energy. You can find data, analyses, forecasts, charts, graphs, and figures for topics like energy consumption, energy production, transportation, climate change, and energy trends.
The National Air and Space Administration's Global Change Master Directory. NASA has hundreds of useful pages on its sites, but this one is particularly helpful because it is set up as a search-able directory of earth science topics. You can select subjects to browse, or type in a keyword.
The American Petroleum Institute. This Web site of the American Petroleum Institute contains an energy consumer section that covers oil and natural gas products, industry statistics, energy related issues, the environment, energy education, and new technologies. This site also has a good page of links to other useful resources.
The National Energy Foundation. This section of the NEF site provides energy resources for educators, including teaching materials, workshops and training opportunities, online energy lessons and activities, and links to other related Web sites.
The Union of Concerned Scientists. UCS is a nonprofit group composed of scientists and citizens working to improve our global environment. On this site you'll find a special section on Clean Vehicles.