A network of public and private organizations founded in 1999 to increase the awareness of the economic, social, and environmental benefits of green roof infrastructure.
Roofscapes, Inc. is a green roof engineering, design and installation firm based in Philadelphia, PA. See the "Case Studies" page under Projects for examples of green roofs they've planned throughout the United States.
The International Green Roof Association (IGRA) is a global network for the promotion and dissemination of information on Green Roof topics and Green Roof technology. Be sure to see the "Green Roof Database" page.
Pomegranate Center is a nonprofit devoted to community-generated design and development based in Issaquah, Washington. This manual includes a good introduction to understanding the benefits of roof gardens, as well as tips for building your own.