There are many bodies out there willing to certify how green you are. A new one is called Degree of Green. The idea is to rate your company according to 3 main criteria: health impacts, environmental impact, and sustainability. Based on these ratings you can provide consumers with some of their marketing material to indicate where your company rate's on these three dimensions.

What is interesting about this effort is that it makes the point that "being green" isn't a one-dimensional concept; that at the very least it consist of environmental, health, and sustainability dimensions and that comsumers may be more interested on one dimension versus another or particular combinations.