Book: Creating XPCOM Components

Doug Turner and Ian Oeschger have released "Creating XPCOM Components", 
a book about Mozilla and about creating XPCOM components for Gecko-based 
applications. The book is principally a long tutorial that describes the 
steps you take to make your C++ code into a component that can be used 
in Gecko, but it also discusses all of the tools, techniques, and 
technologies that make up XPCOM.

The book is arranged so that you can follow along and create your own 
components or learn about different XPCOM topics individually, as in a 
reference work. For example, the introduction includes a discussion of 
components and what they are, and the first chapter-in which you compile 
the basic code and register it with Mozilla-prompts a discussion of the 
relationship between components and modules, of XPCOM interfaces, and of 
the registration process in general.

The top of each chapter provides a list of the major topics covered. 
Sidebar sections are included to highlight technical details. By the end 
of the book, if we've done our job, you will have leaned how to build a 
component, and you will know something about the framework for these 
components in Gecko.

http://www.mozilla.org/projects/xpcom/book/cxc/