Earth Trends
From the site: "EarthTrends is a comprehensive online database, maintained by the World Resources Institute, that focuses on the environmental, social, and economic trends that shape our world."
FuelEconomy.gov
Everything you need or want to know about hybrid vehicles, gas mileage, green house gas emissions from vehicular traffic, fuel economy ratings, and more.
Grist Magazine
If you read just one online enviro news mag, this is it. Their tagline: "Gloom and doom with a sense of humor." Just take a look -- you'll get hooked.
National Campaign for Sustainable Agriculture
It's not just about finding a way to carry on with current energy consumption only minus the emissions. Sustainability, or the lack thereof, touches all national systems, agriculture being one of the largest. Topics include pesticide use and corporate organics, fair trade, food sovereignty, genetic engineering, irradiation and more.
Redefining Progress
This time the discussion centers on economics. Click on "Sustainable Economics" for an interesting twist on the "Gross National Product" -- here it's called the "Genuine Progress Indicator" and factors in such things as volunteer work, crime stats, environmental degradation, public infrastructure, state of leisure and so on.
Center for Small Business and the Environment
Some sample keywords for researching sustainability in Power Search:
corporate social responsibility
economic development
ecosystem management
energy policy
environmental economics
environmental management
environmental monitoring
environmental policy
environmental protection
environmentalism
fair trade
fair use
forest management
globalization
groundwater
human ecology
industrial management
natural resources
social responsibility
strategic planning
sustainable agriculture
sustainable development
sustainable forestry
water resources development
water supply