Personally I have never liked the idea of a middleman when it comes to charity, among other things. Similar to how micro payments can work well only with really low transaction fees, charity needs a low overhead to make proper sense. If your goal is to help small organisations that need donations, then improving on micro-payment technology would be a good start. In fact, this could better allow individual contributors of open-source projects to be compensated, which is something that has been needed for a long time now. If you think about it rationally, who is currently being compensated the least for their efforts -- individual hands or the central websites that benefit from these hands?