I liked how in Freakonomics (I think), they interviewed someone who worked at a hospital, and would regularly and randomly take culture samples of nurses' and d

I liked how in Freakonomics (I think), they interviewed someone who worked at a hospital, and would regularly and randomly take culture samples of nurses' and doctors' and administrators' hands. The results of the culture were shown on a screensaver. This feedback and public transparency was both amusing, and enforcing of the necessary handwashing.