My beginner's Drupal 7 book: What's missing?

I've been busy writing Drupal 7: Visual QuickStart Guide for Peachpit Press over the last couple of months. I'm pleased to say that all the main chapters are done, and most of them are already available for preview on Safari Books Online. (I've given the table of contents below.)

Now it's time to write the appendices, and I'm not sure what would be most useful. We're thinking:

Extending Drupal, including a list of the most popular modules, and whether they're expected to be available for D7 (thanks to the #D7CX project)
Differences between D6 and D7
Interacting with the Drupal community

Other ideas?

Here's what the book contains so far:

Chapter 1. Getting Drupal Up and Running

Fulfilling Drupal's Requirements
Downloading and Unpacking Drupal
Creating the MySQL Database Using phpMyAdmin
Installing Drupal

Chapter 2. Establishing Your Drupal Site

Performing Common Post-Installation Tasks
Giving Your Site Its Identity
Selecting a Visual Theme
Monitoring Your Drupal Site
Packaging Your Drupal Site

Chapter 3. Creating and Managing Content

Gaining More Control of Individual Nodes
Creating Other Types of Content
Finding, Editing, and Deleting Content

Chapter 4. Customizing Content

Defining Custom Types of Content
Putting Images and Styled Text in Content

Chapter 5. Making Content Interactive

Enabling Interactive Content Types
Categorizing Content with Taxonomies
Mastering Text Formats

Chapter 6. Improving Access to Content

Making Content Searchable
Directing Traffic with Menus
Laying Out Your Site with Blocks

Chapter 7. Wrangling Users

Managing User Accounts
Controlling How Users Interact with Their Accounts
Defining User Roles and Permissions
Building and Protecting User Community