This post is 2nd in my series "Library Team Task Force", a description of roles performed by librarians (sometimes the same one!) so that we might come to a better understanding of what our colleagues do and so students might have more realistic ways to potentially decide which track to focus on.
Quick: who do you go to when you walk into most libraries? A reference librarian. Chances are, they get more circulation questions than the circulation desk (especially if there happens to be a line at circulation), plus all the reference questions they field in person, and via telephone and email.
Reference librarians can get the reputation of the "cool librarian" because they're the ones who know where the Anarchist's Cookbook is, where you can find information about things like pornography industry statistics, and why men have nipples (hint: there's a book for that!); from the patron's point of view, the reference librarian can get you answers to questions you'd never ask another person, and show you how to get it yourself in case you don't want to ask why that itches next time (disclaimer: see a doctor, not a librarian, for any and all medical questions). They boldly go where information lives, returning victorious with an answer in their hands.
Reference librarians also, in my experience, have a high rate of burnout. Besides answering questions, they keep stats about all the work they do. They have to be politically savvy, or should be, at any rate, and learn how to balance needs of "normal" patrons with needs of VIP patrons. They need to learn about what exactly the First Amendment covers when it's a minor asking a question, or how to deal with someone who either as a joke or in earnest wants to know where to buy drugs or hire a prostitute. Reference librarians face tremendous pressure from both outside and within the profession to provide information regardless of their personal feelings. A classic example: should a reference librarian who also happens to be Catholic be required to assist a patron in finding a clinic that performs abortions? Should a reference librarian who suspects a patron is severely depressed also help that patron find information about methods of suicide? Ideally, these questions are answered in policies and the library director/manager is available to escalate the situation if needed. Ideals don't always happen.
Reference librarians do what our lofty goals tell us is important: they match those who have information needs with information that meets those needs. They see sides of enquiry that other types of librarians don't, but they also deal with sides of our patrons we might rather not meet. It's a high calling, but the job can be stressful and, from what I've been told, sometimes disappointing because of patron attitudes toward scholarly work and repetitive questions about the location of the bathroom. This job isn't for every personality, so ask yourself if you can deal with the types of "boring", "everyday" questions that make up a fair amount of reference work.