From the simple, to the profound to the life changing, design ideas and solutions are making a difference in the lives of millions around the world. Residents of Bogota, Colombia, show the world a new way to move around. Volunteer health workers in Bangladesh use a portable pharmacy to treat millions of people. An international team discovers an answer to Africa's AIDS epidemic may already be in people's hands. And in Kenya, one man finally unlocks the way to turn a refuse problem into a fuel solution.