Crypto
Steven Levy
Development of cryptography
Firewalls and Internet Security
William R. Cheswick, Steven M. Bellovin, Aviel D. Ruben
For IT admins or IT admin wannabees
Hacking Exposed
Joel Scambray, Stuart McClure, George Kurtz
A key key key source of security
Secrets & Lies
Bruce Schneier
Maybe the most thoughtful security guru
The Resilient Enterprise
Edited by Paul Massiglia and Evan Marcus Veritas Software Corp
How to create appropriate backup architectures