Companies are already making plans for Earth Day. There will be nationwide events and media opportunities to show corporate concern for the environment and their communities. Depending on one's viewpoint, Earth Day will be a PR obligation or a marketing event to show how your product will save lots of trees.

Having successful green initiatives and sustainability programs can have a powerful effect on brand loyalty and brand awareness. And that can truly drive some positive social buzz.

The best green marketing campaigns of 2010 and where they can go next.

There are different approaches to attempting behavior change, such as incorporating prevention strategies into outreach efforts or instituting programs and policies to drive specific behavior. Working to establish and convey certain social norms -- or accepted standards for behavior -- can also be particularly effective.