Plan International, who I've recommended, was founded in 1937. Here's some blurb from their site :
"Plan is an international, child-centred development organisation with no religious, political or governmental affiliations. We work with 1.3 million children, their families and communities in developing countries all over the world, implementing projects at the grassroots level in health, education, water and sanitation, income-generation and cross-cultural communication."
Looking at the Compassion site, they seem to have a strong Christian slant. In fact, this is what they say:
"Compassion International exists as an advocate for children, releasing them from spiritual, economic, social and physical poverty and enabling them to become responsible, fulfilled Christian adults."
Maybe I am misconstruing the Compassion website's message, but to me it seems dangerously close to the old colonial missionary approach of freeing the natives (sic) from their heathen beliefs.