For two weeks, all advertising signs, slogans, pictograms, company names and logos disappeared from a street in Vienna, Austria (Summer 2005):
http://www.steinbrener-dempf.com/The artist explains how the normally "chaotic" and "disjointed" landscape, littered as it was with advertisements, became clean and soothing for 2 weeks!
Awesome.
Also, this reminds me: I was reading about some famous American pioneer in advertising (he was really successful in 40's - 60's). Anyway, he said that in the future, our citiyscapes and landscapes will be so littered with advertisements that developers will create private "ad-free" zones. He felt that folks would pay for the luxury of living, dining and playing in these ad-free zones.
I don't think he's that crazy. I'm just hoping that we'll have public "ad-free" zones as well (put our tax money to good use, for once).