I came across this article from several years ago, that explains how booklets can be a useful marketing tool. There are some really attractive photos of impressive layouts that are inspiring to designers and marketers alike:
"Brochures and booklets are a standard tool for promotion and advertising. They are tiny books or magazines which lay around in conference halls, offices and waiting rooms. Sometimes they contain an annual report of the company or showcase the portfolio of an artist. Brochures can also be included in CDs and DVDs; however, usually they are given away as freebies (e.g. they may contain a calendar or some poster inside)."