Bill Gates personally funds the UN Population Fund which in turn funds forced sterilizations and forced abortions in third world countries.
Well, I've followed your links and remain unconvinced. I am sure I have given big chunks of my wealth myself to Charities which maybe haven't used the money quite as I had hoped (I can think of one story relating to the recent Asian Tsunami, where one charity I gave too did something staggeringly stupid). That said, on balance, UNPF probably does more good than harm and the example you cite in peru was clearly just an example of misapporiation.
They guy doesn't have to give any of his wealth away. He does. By and large the money he gives away does a great deal of net good. Whatever else his faults, cudos to him for that.