The AAP's site leads you to the Section on Community Pediatrics and the Section on International Child Health. Both worthwhile.
Social Medicine - Great online journal
Association of Clinicians for the Underserved
Migrant Clinicians Network
World Health Organization Commission on Social Determinants of Health - Final Report. Closing the Gap in a Generation: health equity through action on the social determinants of health.
South Texas Environmental Education and Research (STEER) Program-Harlingen
Open to students from accredited U.S. medical and health professions schools with a focus on public health and environmental health issues.
Along Side a Border - Mike Seifert's blog
Society for Equity in Child Health (SECH)
Children’s Rights Information Network
CRIN is a global children's rights network. We press for rights - not charity - and a systemic shift in how governments and societies view children. We link to 2,227 organisations and have 22,574 resources on our site at Children’s Rights Organizations.