The Linux Documentation Guides

Linux Dictionary
Linux Filesystem Hierarchy
The Linux Kernel Module Programming Guide
LDP Author Guide
Bash Guide for Beginners
Introduction to Linux - A Hands on Guide
Advanced Bash-Scripting Guide
EVMS User Guide
Custom Linux: A Porting Guide - Porting LinuxPPC to a Custom SBC
Pocket Linux Guide
The Linux System Administrators' Guide
Linux From Scratch
Securing & Optimizing Linux: The Ultimate Solution

And much much more - this is THE site for some awesome info and guides

http://www.tldp.org/guides.html

Oh - and look down the bottom for available language translations