I found the use of two colours on this poster attention grabbing. It has all the important details on and it and one main focus.
Social/Political Posters - Graphis
charity: water poster is short, sweet, to the point - and makes a hard hitting impact about the company's purpose.
Print Advertising: Innovative posters launch new UK youth charity http://blog.solopress.com/design-guide/print-advertising-innovative-posters-launch-new-uk-youth-charity/ #charity #poster
Yes We Can (recycle) Poster
Viva con Agua #Charity #Bottle Poster | http://www.gutewerbung.net/viva-con-agua-charity-bottle-poster/ #Advertising
Amnesty International poster #amnestyinternational
12 South Farmers Market Poster
Amnesty International Posters by Fons Hickmann M23