The National Museum of Emerging Science and Innovation (Miraikan) in Tokyo has a special exhibition, Toilet!? — Human Waste & Earth’s Future that " invites visitors to get to know their poop, describing the types of excrement humans produce, creative ways to use toilets, how toilets work in space, ideas for recycling our waste and details of sewage systems."
It has this grand entrance, where kids wearing little poopy hats climb into a toilet. "There’s a toilet that complains, toilets that sing, and if your kids are being really crappy, you can flush them down a toilet slide that leads to a virtual sewer world."
There is a serious side to this; according to the museum website, 2.5 billion people do not have access to a toilet, and sewage disposal is a serious problem worldwide.
Sewage that includes excrement cannot be discharged into the sea, it should be cleansed, but it includes phosphorus - a precious resource. In Japan, phosphorus is removed from sewage to reduce its effect on the ecosystem; Japanese sewage is almost completely cleaned, but at an energy cost. If we could devise a system that can remove and utilize resources from excrement, we could reduce the effect on the environment and obtain those precious resources.