Cambridge Tree Project: Organization of citizens' groups and individuals working together to assist the City of Cambridge in building support for the protection and management of community trees. Site includes census of street trees, tree care guidelines, tree-related ordinances, and much more information.
Charles River Conservancy: Advocacy group dedicated to the reburbishment of the Charles River basin parklands.
EcoLogic Development Fund: Organization conserving threatened wildlife and wildlands by advancing community-based development and natural resource management in Mexico and Central America. Includes project descriptions.