When you do a search on the University of Michigan Library's web site, you get not only results from the catalog, web site, online journal and database collections, and more, you also get a librarian who is a subject specialist related to your search term. While the matching is not perfect, it provides a human face on search results.
So, for example, if you search for "Kant," in addition to books and databases, you also get the subject specialist librarians for humanities and philosophy. A search for "Jupiter," you get the subject specialists for Astronomy & Astrophysics and Humanities (after all, we don't know if you're searching for the planet or the Roman deity). When we can't make a reliable match to a subject specialist, we provide a link to Ask a Librarian, our reference service.
How does the matching work?
The University of Michigan library has long maintained a database of Library of Congress Call Numbers and "Academic Disciplines" -- which is what we call our subject taxonomy. (You can see it in action in the site's Browse function.) These categories broadly mirror the schools and departments at the University of Michigan. Librarians have assigned Library of Congress call numbers to each academic discipline. This mapping was originally done for our New Books tool so that students and faculty could find out when a new book related to their area of study was acquired by the library. A single call number can be assigned to multiple Academic Disciplines, so a given book could appear in multiple places. In a site search, we do a special query of the library catalog behind the scenes and get the first 100 catalog results (sorted according to the catalog's relevance ranking algorithms). We sort those results into Academic Disciplines. If more than 25 items are in a single Academic Discipline, we include the subject specialist responsible for that particular area. (We set the threshold at 25 matches to help ensure a relevant match, but a librarian specializing in the "wrong" subject is arguably better than no librarian at all.) We make the call number-to-academic discipline mapping available on our site at http://www.lib.umich.edu/browse/categories/. There is also an XML version of the mapping free for all to use or adapt.