WikiLeaks exposed Scientology, a religion that scams its followers into a delusional set of beliefs in exchange for their money.

March 11th, 2008
http://yro.slashdot.org/article.pl?sid=08/03/11/2348242

WikiLeaks has revealed the National Socialist Movement's neo-nazi internal workings.

August 21st, 2009
http://boingboing.net/2009/08/21/wikileaks-publishes-1.html

WikiLeaks released a video showing a U.S. army helicopter slaughtering Reuters journalists and Iraqi children in cold blood.

April 3rd, 2010
http://youtube.com/watch?v=5rXPrfnU3G0

Source: sowhyiswikileaksagoodthingagain.com