One of my last jobs at Leo Burnett was to work on a campaign for our pro-bono client "Greensaver". They are a company that does energy efficiency audits on homes to ensure that they are as environmentally efficient as possible. Not just to be socially conscious but to save you money (that's my sales pitch!).
Anys... we did this transit/subway poster campaign for them- which is in market right now. It's definitely different for the category as it's light and tongue in cheek- versus all the usual heavy handed "we're all going to die unless you change to energy efficient lightbulbs!!!" rhetoric.
Here is the online banner ad featuring yours truly...It's kind of small and when I get a copy of the final image I'll post it as well. The thought bubble says "Now my carbon footprint is as stylish as my shoe collection."