Contextual Design: Defining Customer-centered Systems. Hugh Beyer and Karen Holtzblatt.
This is one of my favourites; it more Post-it notes sticking out of the top than any other on my bookshelf. That's because there are so many insights inside that I do not want to lose. Please do not be misled by the word "design" in the title. The important part of this book is about contextual inquiry, where the developers work with the users to understand the work needs before attempting to design anything. Beyer and Holtzblatt give us a raft-load of ideas on how to get close to the customer, and how to understand what is really going on.
Contextual Design places great faith in the customer data - information and understanding of the customers and how they work. "Without a clear understanding of your customers, based on real events rather than anecdotes, and captured explicitly, you have no criteria for deciding on one action or design decision over anotherÉ.. But customers cannot tell you the important aspects of their own work practice because they are implicit and unrecognized. ÉContextual Inquiry reveals the hidden aspects of the work practice; paper prototyping reveals how a particular design plays out in the real work context."
This book is highly recommended for business analysts, and anyone whose work is understanding work.