The AAS is one of many professional organisations actively supporting more sustainable and environmentally-friendly practices; we hope to work closely with them in the future.
NASA has a comprehensive Strategic Sustainability Performance Plan "to execute NASA’s mission without compromising our planet’s resources so that future generations can meet their needs."
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 Acadamies, advisers 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."
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 observatory by 30%. Investigating, quantifying and adjusting a wide range of activities and behaviours, this programme is a model for other institutions to follow.
Originally used to write the astro2010 white paper, 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.