I did a Master of Environmental Science in 2006 with a focus on engaging university students in sustainability initiatives on campus along with how we go about trying to change people's behavior to act in more environmentally responsible ways. I then got a job as a research fellow for one year working on a related project and I now work for the university's sustainability office on student outreach and education projects. I LOVE my job! It's great to do something you love and feel like you make a difference every day. Well most days :) This sector is growing in leaps and bounds with many campuses hiring dedicated sustainability staff. See the Association for the Advancement of Sustainability in Higher Education (AASHE) at http://www.aashe.org/ for more info on this field. Their bulletin offers job listings as well.
Consulting and environmental education are other interesting avenues. Whatever you do, be sure you get strategic skills so you can market yourself well. GIS, survey skills, soil or water testing, education credentials, research methods, organizational change strategies, etc.
All the best!