Architecturally, a prime example of sharing facilities is what is known as co-housing. With this, a group of people agree to live in a housing situation that is designed so that each family unit has their own basic living accommodations, which are private, but then there are other facilities used in common. For instance, each family might have their own bedrooms, bathrooms, living room and small kitchenette, and then all of the residents might share the use of laundry facilities, meeting room, recreation room, swimming pool, a large kitchen and workshop.
Other modes of living in a cooperative group are intentional communities or communes and eco-villages. Any living arrangement where people share facilities can be beneficial.
There is a social benefit to living in community that is often of considerable appeal to the residents. With the changing make-up of our society, the single-family unit no longer defines how many of us choose to live. People often prefer to be solitary, or at least find themselves in this condition, and becoming part of a larger group can give them a sense of belonging, without the extreme intimacy of marriage.
With co-housing and other community arangements there is often the added advantage of the preservation of open space around the development. The greater density of housing can mean less impact on the environment. Here we have a winning situation for both the residents and the earth!
There is a new page at my website, http://greenhomebuilding.com/sharefacilities.htm, with descriptions of several books related this, as well as a collection of links for more information.