Simple easy-to-use how-to full of tips-n-tricks for automating, configuring and customizing firefox to your specific needs.
Table of Contents is good with 2 versions - At-A-Glance and Detailed so you can just scan it for your current needs without having to go through the entire book/index.
Gives enough background info to get you started and understand how firefox works.
This approach helps you tweak it just so.
