I can bet everyone has their one favorite book even though we have had read many books on UNIX or Linux. My all time favorite is "Unix Power Tools". This book always made me geeky and I loved the little tricks/tips in the book. I still do!
The next favorite would be "Prentice Hall Unix and Linux System Administration Handbook".
Even though we get carried away by virtualization, zones, LPAR, nPAR, vPAR, and God knows what more, we still feel a little nostalgic when somebody talks about age old chroot or BSD jails, dont we?
So what's that book of yours that always gives you reason to know more?