In seriousness, GiveWell ranks charities by their effectiveness. You could give to one of their top charities: http://www.givewell.org/charities/top-charities "These are evidence-backed, thoroughly vetted, underfunded organizations."
Edit: (in reference to z3ugma's comment) further down that page is actually a charity whose mission is to aid salt iodization programmes in developing countries. I honestly had no idea this was even an issue until now.