Resources on environmental/green business:

• ABI/Proquest: search for articles on topics related to green/eco/sustainable startups, and on green business or startups in general.
• Green Entrepreneur Handbook: Guide to Building and Growing a Green and Clean Business: ebook available at Harvard.
• Ecosummit: A green business network that provides talks from green business related conferences.
• SoundCloud: search SoundCloud for related podcasts using "environmental startup," "green startup" etc.
• EPA's Lean Practices: Toolkit for companies getting started with the EPA's Lean & Environment initiative
• HBS's Business & Environment Initiative: Find new faculty research in this area, news, discussions, and more.

General startup resources:

• Wharton Stories: Entrepreneurship Toolkit (Video): Herb Fockler from Wilson Sonsini Goodrich & Rosati and Russ Keefe from Animoto Inc. identify a wide range of resources for entrepreneurs
• U.S. Small Business Administration: A business guide, and information on funding programs, contracting, local assistance, etc, for startups and small businesses. 
• HOLLIS Catalog: Books on startups available at Harvard.
• HBS Working Knowledge: Entrepreneurship: Find new HBS faculty research on entrepreneurship.
• Baker Library's Entrepreneurship Toolkit: Find databases and other resources from Baker's collection to help with startup development.