Tutorial - How to create a simple Firefox plugin from scratch in 10 minutes
Build Your Own Firefox Extension
Creating Custom Firefox Extensions with the Mozilla Build System
http://pyxpcomext.mozdev.org/
https://developer.mozilla.org/en/Code_snippets
10 Things They Never Tell You In Firefox Extension School
How to build a binary XPCOM component using Visual Studio
XPCOM components, extensions and Visual C++ Express
Mozilla Platform - XPCOM in C++
Accessing the Windows Registry Using XPCOM
How to write C++ XPCOM components
mozilla, developer center, Creating XPCOM Components
XPCOM Part 1: An introduction to XPCOM
XPConnect is a bridge between JavaScript and XPCOM.