Screening of "the end of the line" at my office today. Organized by the WWF, the documentary is about overfishing with an eco-conscious theme. Suddenly have an urge to go out and start gulping down blue fin tuna before they ban it. Just kidding, buy only from companies with sustainable fishing practices. Homepage: http://endoftheline.com/.
The World Wildlife Fund is really a good cause. You can find out more about how you can contribute as a consumer or donate directly at http://www.worldwildlife.org/home.html. Alternatively, you can buy the WWF Faberge Eggs (where 15% of proceeds are donated) or the annual edition of soft toys from Build-A-Bear Workshop.