Linux Server Hacks: 100 Industrial-Strength Tips and Tools
Rob Flickenger
O'Reilly Media
This book shows its age (which is quite expected since GNU/Linux is such a fast moving target) but still includes some good tips and tricks for system administration and advanced level use of GNU/Linux systems. If you're some who really need this book then you'll also need 'Linux Server Hacks, Volume Two: Tips & Tools for Connecting, Monitoring, and Troubleshooting'.