This is a collection of technical docs that I've found useful. Most of these are written by other people. Refer to the authors' pages for license information.
Written by me
Slackwiki article I wrote explaining installation and auto-update of Google's Chromium web browser on Slackware.
Another SlackWiki article. This one explains how to install Broadcom's proprietary wl wireless driver on Slackware.
After wrestling with several console and GUI mail clients, I solved all my email headaches using Mailx. This is a how-to for setting up Mailx with Gmail, instructions for handling MIME and PGP included.
Using a Linux Desktop with KDE --In Progress--
A guide for Windows users who want to learn Linux. Starting from the basics, I explain the usage, differences with Windows, advantages and common annoyances of a KDE 4 desktop.
Written by others
RUTE user's Tutorial and Exposition by Paul Sheer
This is the book I link to whenever someone says, "I want to learn Linux". A tutorial for new users and a reference for advanced administrators.
Note: The PDF link on the author's website is broken, so I have mirrored the file.
Apache Web server - Complete Guide by Igor Ljubuncic aka Dedoimedo
Great, detailed book that explains installation, configuration and deployment of the popular Apache web server. Written for CentOS, but easy to adapt to any Linux or BSD variant.
How to do backups by Jamie Zawinski
Simple, down-to-earth advice on how to do backups.
This FAQ is awesome. Read it. Everything you need to know about OpenBSD is in it. Read it even if you don't know what OpenBSD is, or don't want to use OpenBSD, it's just that good. This FAQ teaches you how technical documentaion ought to be written. In fact, it will also teach you that documentation needs to be written.
Mercurial: The Definitive Guide by Bryan O' Sullivan
Good documentation is important. Mercurial has it, Git and SVN don't. Written in simple, down-to-earth language, this book does not discriminate. A great read for everyone who wants to know about Mercurial, or Distributed Revision control systems in general.