Doctors Without Borders/Médecins Sans Frontières (MSF) is an international medical humanitarian organization working in nearly 70 countries to assist people whose survival is threatened by violence, neglect, or catastrophe.
HABITAT FOR HUMANITY ... http://www.habitatforhumanity.org ... Interest-free mortgages given to homeless families who work alongside volunteers to build their own home - a brilliant idea brought to glorious life! IMO, one of the greatest "pull yourself up by your bootstraps" kind of non-profit in America.
I’d just like to give a general plug for this site that promotes ways for teens to improve their communities. Any kid, even pre-teens, who is interested in community/world service will find ideas and inspiration here.