Microsoft founder and history's biggest philanthropist Bill Gates has a new obsession: toilets. He and his wife's foundation launched a "Reinvent the Toilet Fair" in Seattle on Thursday, awarding prizes for new sanitation innovations. "Toilets are extremely important for public health and, when you think of it, even human dignity," Gates said in a statement. The fair attracted hundreds of investors, inventors, and researchers, and the California Institute of Technology walked away with first place, for a solar-powered toilet. "Inventing new toilets is one of the most important things we can do to reduce child deaths and disease and improve people's lives," Gates said.