Many of the more advanced Linux books out there focus on programming, scripting, and administration. While I'm not a developer or an administrator, I've found the next two books very useful.
The first is Linux Shell Scripting with Bash by Ken O. Burtch. A shell is an environment you can type operating system commands -- one of the more popular of them is Bash (Bourne Again Shell). Scripting enables you to combine and run commands in useful and novel ways.
This book takes your through the basics of shell scripting. It shows you how to use basic shell commands, and how to include them in Bash scripts. From there, you learn to pull these elements together to manipulate files, use scripts to combine multiple commands, and use those scripts to maintain and administer your system. For the techie, there are chapters on using scripts with Web services and databases.
Linux Administration: A Beginner's Guide by Wale Soyinka is another useful book for the advanced user. While I generally look for Linux books that don't focus on a particular distribution, this book is an exception. It covers Red Hat Linux, but the techniques it presents can be applied to other distributions.
The author explains how to install Linux, as well as set up and manage user accounts. On top of that, you'll learn how to configure and manage various Internet services, set up a Web server, configure network sharing, and even how to get Linux to talk to Windows. There are even instructions on setting up and maintaining firewalls.
All of this sounds pretty technical, and it can be. But, Wale Soyinka does a good job of making the content of the book easy to follow.