Ban Billboards..
gets my vote...
Back in December, 2006, the mayor of the 11-million-person Brazilian city of Sao Paulo banned all outdoor billboard advertising, citing advertisers' unwillingness to comply with the city's rules on what sort of billboards can be placed where. Now the rule is in effect, and Flickr user Tony de Marco has documented the eerie sight..
http://www.digg.com/design/PICTURES_Sao_Paulo_Goes_Advertising_Free