As a journalist reporting on China, Sheryl WuDunn saw the everyday oppression of women around the world. She and Nick Kristof wrote "Half the Sky," chronicling women's stories of horror and, especially, hope.
Journalist Andrew Mwenda has spent his career fighting for free speech and economic empowerment throughout Africa. He argues that aid makes objects of the poor -- they become passive recipients of charity rather than active participants in their own economic betterment.
Tim Jackson is a British ecological economist and professor for sustainable development at the University of Surrey. He is the author of "Prosperity without Growth" and director of the Centre for the Understanding of Sustainable Prosperity.
Ernest Madu founded the Heart Institute of the Caribbean, a revolutionary clinic for cardiovascular diseases in Kingston, Jamaica -- revolutionary for offering first-class health care in a developing nation. His next stop: Nigeria.