I love the idea of using Pinterest to document all the activities of a library. There are so many events and projects unfolding in libraries that can be shared through a single picture on Pinterest, such as, display boards, reading events, competitions, reading room designs are all accessible to see and promote on this media. This is a place where librarians can go to share and find ideas for different aspects of the library.
It can be used for public or University, and gives clever ways of engaging and encouraging patrons to come to the library and experience how great an institution it is. It is difficult to capture the attention of a browser on the internet but a picture can capture a moment in way that no blog could. The picture is also a quick visual stimulation that can draw a browser in to a library or at least have them research a little more about the library. Using art to promote art.
Pinterest can be a bit messy and difficult to navigate because of the amount of information it has on the site, however the deeper you explore the more detailed and clearly classified your findings become. I would recommend having a look at Louis Robidoux Library on Pinterest at https://www.pinterest.com/cabazonlibrary/
Miss Mafimushkila 
The Robidoux Library pinterest page looks really good.