Take a look on the interesting work Hands Face by the photographer Adam Krawesky.
Adam Krawesky started photographing people on the streets of Toronto in the summer of 2002 [..] he asked to photograph them with their hands covering their faces, to assuage his own fear of confrontation and the stranger’s suspicion of the lens. […] What I notice is the truth that comes through from the hands and the postures of the people behind them. The play-acting of hiding reveals more than a common portrait might ever reveal.
(via The Wandering Jew )