I'm not actively involved in this nonprofit, but I give to it monthly and would encourage anyone wondering how to stretch their impact to consider donating as well. TLYCS was founded by Peter Singer, a modern philosopher and professor of bioethics at Princeton who contributed massively to the effective altruism movement. His organization carefully assesses the impact of a wide range of nonprofits and has set up funds to ensure every dollar donated spread around to achieve as much good -- that is, reduce as much suffering -- as possible.