Popular job boards:

• American Fisheries Society
• California State Government (Coastal Commission, State Parks, Coastal Conservancy, Ocean Protection Council, SF Bay Conservation and Development Commission, State Lands Commission, etc.)
• IUCN – SevenSeas
• Society for Conservation Biology
• Consultative Group on Biological Diversity
• EarthWorks – Oceanography, Paleooceanography, Marine & Coastal Science
• EURAXESS – European Jobs
• Environmental Science.org
• Green Jobs Network (NEW) = Multiple websites for conservation, environmental, energy,  water jobs and more (Mostly UK)
• Green Job Search – Sustainability & Environmental Jobs
• National Association of Marine Laboratories (NAML) job board
• Ocean Associates
• Schmidt Marine Job Board (Thanks Davey)
• Sustainable Business.com
• USA Jobs – The US Government Job site
• Science Careers
• Association of Zoos and Aquariums

Recommended job search sites that require registration

• Biology Jobs.org – All Life Sciences
• Brad Traverse – Capital Hill jobs
• StopDODO – Environment Jobs for Green People (many in Europe)

Prepare your CV or Resume:
Science Careers: How to Craft a Winning Résumé:
http://sciencecareers.sciencemag.org/tools_tips/how_to_series/how_to_craft_a_winning_resume