The Urban Forest Project

The Urban Forest Project, as the name suggests, is all about saving the trees and spreading the message in various cities. The project is a visual statement that consists of displaying banners from actual designers and design students in cities like New York, Baltimore, Denver and more in the works. Your city can get involved.
http://www.ufp-global.com
Below are some banners from designers. There is lots more inspiration on the Urban Forest Project individual city websites.

Rob Alexander

Clarissa Tossin

John Pirman

Chad Miller