I had a student from one of the local colleges come in today. She was doing a paper on the history of the local lumber industry, and one of the founding members in particular.
Last year, as part of my growth and development, I put together a bibliography of all books about My County that aren't in the section that most are in (977.447). This includes biographies, some sports books, family histories and all together, a full six pages of titles, call numbers and authors.
Using my 'Master Bibliography', I was able to find her three books on the lumber industry and the illusive biography of the founding member in under two minutes.
If I hadn't had the bibliography, it would have taken me a few more minutes if I'd chosen the right keywords, and longer still if I hadn't.