Just got a request to describe my activities as a part-time reference librarian. Here's my response:
Basically the part time job is totally reference (i.e. public service) work. Questions run from 'where is the copier/bathroom/color-printer' to 'I'm writing a research paper on advances in chemistry in the 18th Century and need to find some research articles'.
Am I an expert on advances in chemistry in the 18th Century? No, but I know where to get the student started and I can also show the student how to find articles and, equally as important, how to evaluate search results so that they branch out into even better material. I also know, finally, what the limits are and who and when to refer them to other people.
That's pretty much what I do.