What goes into a loudspeaker?

I have built a couple of loudspeakers in the past 18 months, but they were very simple affairs: one driver, no crossover, and an open baffle.  But I aspire to make "real" speaker cabinets.  I have a good book, the Loudspeaker Design Cookbook (LDC), but I am also looking for more inspiration, and more options.  One challenge to speaker design, however, is matching the acoustical and mechanical properties of the drivers with the cabinet design.  One solution, which I will likely use, is building a speaker according to plans, such as those in the LDC.  The company Parts Express also sells speaker kits. 

As for myself, I plan to build my own cabinets.  But I am certainly tempted by the high-quality products available from Parts Express.  Here's a video showing what goes into a basic 2-way loudspeaker.  Interesting, no?