Short and to the point books.
That's the trend you'll notice after reading stuff like The Book of PF, Building a Server with FreeBSD 7 and BSD Unix Toolbox. X Power Tools happily joins the mentioned groups... with distinction.
The book is divided in 15 sections which are further organized into articles going over subjects such as the history of the Xorg server, configuration (how to build a xorg.conf), advanced configuration (including multiple displays) and troubleshooting in the book's Part I.
Client oriented subjects are brought in with Part II, which covers many of the rather unknown applications that are part of Xorg, e.g. xmag, xset, xdpyinfo, xfontsel and many others.
Part III exposes the reader to color, fonts and keyboard configuration.
Using X remotely is covered to a reasonable extent in the book's Part III. Here X tunneling with SSH and VNC are discussed alongside XDMCP and xauth.
In a rather unexpected way, the author chose to wrap-up the book by going over the details of configuring X for a kiosk.
As a side note it was nice to see that the author didn't focus only on Linux but also took into account FreeBSD when writing the book (moused settings are analysed).
It should be pointed out that the book was printed in late 2007, so HAL device configuration of keyboard, mouse and displays aren't discussed. However, in my opinion anyone wanting to read this book has already dealt with the situation and is looking into expanding his knowledge of Xorg into less focused things such as fonts, raw X terminal, xinit, etc.
X Power Tools is very handy and well structured making it a good alternative to those that avoid reading Xorg's extensive man page (such as yours truly).
If the Xorg subject appeals to you buy the book. Though a bit expensive, the book is a must have if you want to dwell on Xorg from a very hands-on approach.