The following is a brilliant, evidence-based lecture on the devastating consequences of socio-economic inequality. The speaker is Richard Wilkinson, an epidemiologist and leading figure in the field of inequality research. The lecture presents a very compelling case for the idea that the level of socio-economic inequality in a society is the key criterion for determining the health of that society. One can also read a brief Truthout interview with Wilkinson on the consequences of inequality here.
http://www.democracynow.org/2012/6/6/joseph_stiglitz_on_the_price_of