What: Human Needs Project, which provides clean water, energy and technology to slums worldwide. They're finalizing their first project, Town Center, in Kibera, one of Africa's largest slums, in Nairobi, Kenya.
Why: After meeting residents of Kibera while shooting a movie, Nielsen was moved to take action.
"They have no access to (the) means to change their lives," she says. "The daily weight of just having to get water, go to the bathroom, take a shower is so enormous, so difficult that they cannot get (beyond) pursuing their basic needs. There are a billion people living like this."