One day Ludwick Marishane and his best friend were sunbathing in the sweltering heat in their native Limpopo. Marishane's friend turned to him and said, "Man, why doesn't somebody invent something that you can just put on your skin and then you don't have to bathe?" Marishane, 17 at the time, thought: Yeah, why not? It took six months of research to develop a formula for a lotion that cleanses cheaply and easily -- especially important for the 2.5 billion people worldwide who lack proper access to water and sanitation.

DryBath has the same effect as anti-bacterial cleanser, but it's odorless and creates a biodegradable film that cleanes and moisturizes the skin. Five years later, it's now available on the market. Marishane has since enrolled at the University of Cape Town in South Africa and was named the Global Student Entrepreneur of the Year in 2011.