I know I'm a bit late jumping in (and hey, first time poster too...) but here's a Table of Contents, based on the ideas mentioned so far - especially the Tasks vs Tools principle hinted at by Little Mac. Consdering Toggie is also working on a ToC, perhaps he can merge the best ideas from his with this (although for some reason I expect there to be many similarities).
I've divided the book in three sections. The first covers basic concepts, not particularly related to Comodo sometimes. This way we can make some assumptions, like the user knowing that the internet consists of a bunch of computers talking together, in the chapters that follow. This section is somewhat tool-oriented.. Second section contains Objectives - things the user wants to accomplish - this takes the Tools vs Tasks one step further... a user doesn't say to himself 'Gee. I really feel like adding a trusted application today!' - he says to himself 'I want my P2P client to work, so I can listen to an MP3 of Bach's Brandenburg Concertos!'. The objectives lead to tasks - the assumption is made that if you explain a task, the user will be able to extrapolate from that task the steps required to perform similar tasks. The third section is more of a 'lookup' directory. It will duplicate some information from the second part, but offer it more in an application-manual style. This way, if you know what you're looking for, you can cut right to the chase.
== SECTION ONE - PREPARING ==
1. Introduction
1.1 How this guide works
1.2 Intended audience
1.3 Shortcuts
2. The Internet
2.1 Connecting to the internet
2.2 Security concerns
2.3 Solutions
3. A Very Shor History of Firewalls
3.1 Dedicated hardware
3.1.1 What about my router? (Note: chapter to explain relying on just a router is a Bad Idea)
3.2 Software
3.2.1 Advantages and Disadvantages to Software Firewalls
3.2.2 Windows Firewall (Note: Get out the sledgehammer and let the bashing begin?)
3.2.3 Types of Firewall (Note: Begin with simple IP blockers such as PeerGuardian on one end, end with CFP V3 at the other end of the spectrum)
== SECTION TWO - GETTING THINGS DONE ==
4. Getting Started
4.1 Choosing a firwall (Point out to users that there ARE actually alternatives to CPF, which might be more suitable for complete n00bs... don't flame too much for saying that

)
4.2 Obtaining Comodo Firewall
4.3 Installing
4.4 What's all this stuff you're asking me?! (Explanation of the popup balloons, etc)
4.5 Application Overview
5. Getting an application to work
5.1 Browsers
5.2 Peer To Peer
5.3 Chat applications
5.4 Games
// Note: Followed by other categories of applications
6. Tightening up security
6.1 Sealing off everything (Block All mode)
6.2 Blocking a particular application
6.3 Blocking a particular computer
6.4 Choosing a security level
7. Understanding Defense+
7.1 Defense+ Events
7.2 Choosing a response to a Defense+ Event
7.3 Protecting your computer from attacks on the inside
8. In case of problems
8.1 Checking if Comodo Firewall Pro is the culprit
8.2 Keeping Comodo Firewall Pro up to date
8.3 Restoring a previous configuration (Note: Applies to v3, I believe)
8.4 Getting help (Note: Explain about Comodo Community)
8.5 Telling Comodo to fix itself
8.6 Submitting files to Comodo
== SECTION THREE - Digging Deeper ==
9. Protected Areas (mostly further explanation of Defense+ I guess)
9.1 Network (Firewall)
9.2 Applications
9.2.1 Processes
9.2.2 Files
9.3 Operating System
9.3.1 Registry
9.3.2 Inter-application communication (COM interfaces)
10. Defining policies
10.1 Security Policy explained
10.2 Policy Elements
10.3 Creating your own policy elements
10.3.1 Network rules
10.3.2 Application rules
11. Why Trust Comodo Firewall Pro?
11.1 Comodo Company History
11.2 Fullpage picture of Melih
11.3 Random selection of Melih's promotional posts here on the forum
11.4 Innovations Comodo brought to the FW market (to establish image of cutting-edginess)
12. .... Out of ideas
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Well.. my arms are aching now from typing this up. Feel free to use it, discard it, change it, etc. Once this thing gets started, I'd be happy to contribute text to various chapters. I would strongly recommend focussing on V3 - that way, when V3 is done, perhaps Comodo will be able to ship this kind of document along with it. Also, while a Wiki is great for working on it, distributing documentation usually works best in a plain old PDF file (due to having it all together in a single, downloadable file) - I would urge you to use a Wiki instead of MS Word .doc (or any other file-based system) for working on it, though.. especially with multiple contributors, such things get pretty messy pretty easily, due to people working on various parts at the same time.
Just my slightly-more-than-€0.02
--K