For instance, where does xmonad installation, configuration, etc go? Do we continue to expand the Slackbook/Slackguide to have an grotesque number of xap installation and configuration instructions?
Yeah, I know what you mean. I'd add another section. See below for my suggestionsin bold
** Startup Guide --- An Overview **
The KDE Desktop
The Xfce Desktop
The Fluxbox Desktop
Other Desktops / Window Managers
Basic Mouse and Keyboard Techniques
Basic Keyboard Shortcuts
Using Dialog Boxes
These three seems Desktop specific so I'd put them under particular DE/WM entries
** Reference Guide --- Some Computer Fundamentals **
A Multitasking and Multiuser Computer System
Security and User Permissions
Creating User and Group Accounts
Shutting Down Properly
Customizing the Desktop
Which DE? Again. IMHO it should by under a particular desktop
Customizing the Desktop for People with Special Needs
Customizing for Multiple Languages
Adding "Quick Launch" Icons to the Task Bar
Not everyone users icons. Tasks bars are configured differently across DEs/WMs. This is DE/WM Specific
Adding Items to the System Menu
Understanding Folders and Files
System Files and User Files
Using a File Manager
Using a Printer
Setting the System Clock
Terminating Programs That Crash or Freeze
Connecting to the Internet
Finding New Programs
Automatically Updating Programs
Viruses and Malware
** User Guide --- How Do I . . . **
Quickly calculate some numbers?
Surf the web?
View a PDF file?
Send and receive email?
Organize my schedule?
Write a formal letter?
Edit basic text files?
Jot notes to myself?
Use special keyboard characters?
Schedule reminders and alarms for myself?
Let the children "paint"?
Do some serious drawing?
Grab a screenshot?
Touch up and edit images?
Draw a flowchart?
Create some charts?
Learn to type?
Listen to music files?
Listen to an audio CD?
Adjust my audio volume?
Either alsamixer or DE/WM specific
Watch DVD movies?
Make backups of my CDs and DVDs?
Rip an audio CD?
Use my USB flash drive?
How do I save camera photographs?
Browse and manage my digital photograph collection?
Download and read RSS feeds?
Chat with my daughter with instant messaging?
Edit my web site pages?
Manage a small-scale project?
** Advanced Topics (Appendices or Separate Documents) **
The Command Line Interface
Installing Multimedia Codecs
Configuring Video Cards and Monitors
Configuring Sound Cards
Configuring Internet and Network Connections
Configuring Page Scanners
Configuring TV Cards
Installing New Software
Installing Firefox Extensions Globally for All Users
Creating A Common File Storage Location
Scheduling System Tasks and Events
Modifying the Bootloader Options
Keeping Slackware Secure
Updating Security Patches
Obtaining Additional Packages
Some Thoughts About Backups
** Administrator's Guide **
Hard Disk Partitioning
Some Unix Basics
The Filesystem Hierarchy and Structure
Command Line Shell Basics
How the Slackware System Boots
Kernel Modules and Devices
Slackware Package Management
Emergency Repair Tricks
System Information and Inventory Tricks
Solving System Problems
Installing Windows in a Virtual Machine
Configuring a Firewall
Configuring a Router and Family Local Network
CPU Frequency Scaling
Managing a Slackware/Windows Dual Boot System
Migrating Web Browser Settings
Migrating Email Settings
IMHO, A lot of stuff is DE/WM specific so I'd organise it around those. Just my 5p