Tears run down the cheek of President Barack Obama as he speaks at his final campaign stop on the evening before the 2012 election in Des Moines, Iowa. It seems a strange sight: The president of the United States, sometimes called the most powerful person in the world, breaking down in tears thanking campaign workers for their tireless — and ultimately successful — work on his behalf. But Barack Obama isn't the only world leader unashamed or unable to avoid being seen crying in public.