Navigando in rete mi sono imbattuto in quello che definirei un bell'esempio di social (e low-cost) advertising e che probabilmente si commenta anche da solo...

Client: Mass Coalition for the Homeless
Project: Outdoor Advertising Campaign

"You don't need a big budget. You need a big idea. This low-cost billboard for the homeless created a stir in Boston and led to a major increase in donations to the Massachusetts Coalition for the Homeless. The ad was published in The One Show, a compilation of the best advertising created worldwide."