The AAS is one of many professional organizations actively supporting more sustainable and environmentally-friendly practices; we hope to work closely with them in the future.
The Department of Energy Blog has an emphasis on sustainability and other department-wide efforts to reduce the energy use of our infrastructure. In particular, the Lawrence Berkeley National Laboratory is actively working to reduce energy use while embarking on cutting-edge research on energy efficiency.
The National Academies, advisors to the nation on science, engineering, and medicine, have an active Science and Technology for Sustainability program "to contribute to sustainable improvements in human well-being by creating and strengthening the strategic connections between scientific research, technological development, and decision-making."
Astronomers for Planet Earth "is a grass-roots movement uniting astronomy students, educators, and scientists around the globe to share their astronomical perspective about the Earth and climate change with the public."
The Union of Concerned Scientists is the leading science-based non-profit working for a healthy environment and a safer world. In addition to up-to-date reports on climate change, nuclear power, and federal legislation, they have produced a comprehensive report available on how to avoid dangerous climate change.
The Gemini "Green Initiative" has been running since 2008 and has successfully reduced the carbon footprint of the Gemini Observatory by 30%. Investigating, quantifying, and adjusting a wide range of activities and behaviors, this program is a model for other institutions to follow.
Originally used to write the Astro2010 Astronomy and Astrophysics Decadal Survey paper "Low Energy Astrophysics", the Low Energy Astrophysics wiki is an online community of green-minded astronomers who are concerned about various aspects of human energy consumption. The Low Energy Astrophysics Google Group provides a forum for this community to discuss sustainable astronomy.
University Corporation for Atmospheric Research (NCAR & UCAR) was launched from a former environmental stewardship program, a volunteer effort that engaged staff in a variety of resource conservation efforts. They are engaged with a wide range of activities, and are looking for more people to get involved!
The Steward Observatory Mirror Laboratory, under the direction of Roger Angel, is developing high-output concentrating solar power generators, using telescope technology. The spin-off company is called REhnu.