Google now has a "Green" options in their mapping service. I would be interested to know if they are getting paid to list places as "green" or if they are doing it just as a service.

http://trex005.googlepages.com/maps.google.com.png

http://trex005.googlepages.com/green.google.png

It looks like a promotion of their Summer of Green campaign, which is partnered with "Earth Day Network":
http://blogoscoped.com/archive/2006-05-31-n64.html