The Bubble Project is an attempt to rouse the rabble to rebel against street advertising. If you go to the website, there is a template to print out stickers with the word balloon above. Then they suggest you go around slapping these stickers on bus stop ads and construction site posters and so forth.
Then you or others fill in snarky sayings, photograph them, email them in, and they'll start a gallery.
This is illegal, so I'm not suggesting you do this. I'm merely presenting this to you as a matter of interest. I personally have no dog in this fight, since I live in L.A., where the blight is mostly of the billboard variety.
This project comes from New York, where I'm sure it's more of a problem... although frankly I'm not sure naked construction site walls are better, but hey, everybody got their something.
If they ever come out with a project against those snaggletooth leaflets... You know the ones with tear-off phone numbers for a Free Salsa Lesson or Dodge Dart For Sale, then I'm on board.