I just finished up a graduate degree in Library Science and we talked a lot about user modeling. This applied to both physical and digital environments.
In the physical realm, you have to put a lot of thought into how your library is set up, where the fiction and non fiction sections will be, how many tables and computers you will have, how the lighting will work. You also need to figure out how you are going to shelve the books. Many alternatives to the dewey decimal system are begin developed to provide an easier user experience.
There is also the digital catalog to consider. This is the way that most people find what they want in a library. In a big system the online catalog gets used tens of thousands of times. User modeling helps software designers develop the most user friendly program possible.