http://www.americanscientist.org/issues/id.5783,y.2009,no.2,content.true,page.1,css.print/issue.aspx
"... suppose you must decide when to stop and choose between only two slips of paper or two cards. You turn one over, observe a number there and then must judge whether it is larger than the hidden number on the second. The surprising claim, originating with David Blackwell of the University of California, Berkeley, is that you can win at this game more than half the time."