I am applying for graduate school to earn my MLIS and found this book to be very helpful. It includes a TON of different careers you can have with your GLIS or MLIS. Each job title includes a salary range, employment prospects, prerequisites, career ladder, position description and tips for landing the job. This is not another vague career book -- it has excellent concrete information. The author has clearly done substantial research for this book.
This book helped me make the plunge. I was worried about getting my MLIS and then not being employed, but this book really gave me a lot of options to explore.