Okay, me first.
Joel on Software
Originally a weblog only, Joel Spolsky writes about the various challenges of software development. He talks about issues like Unicode, scheduling, project management, entrepreneurship, and the like. I don't agree with everything he says, and I wouldn't make it required reading at any organization, but there are definitely some good reads in there. I found the humor... ok. A worthwhile read.
$16.49 on Amazon.com
Secrets & Lies: Digital Security in a Networked World
Crypto legend Bruce Schneier's definitive Applied Cryptography is the tome for understanding crypto. But the book led people to believe that encryption solves all the world's security problems. This book clarifies that misconception. It takes a step back and explains what security really is: risk management. What, exactly, are we trying to secure, from whom, and for what purpose? Those are the quintessential questions, not "Which file extensions should we block?". It's designed to be read from beginning to end, so it's not a reference, and it takes a while to get though.
It's easy enough to read for a non-technical person, too. Biggest downside was that Schneier couldn't help but plug his company, but it doesn't interfere too much. A great read for IT folk and anyone who wants to know what computer security is really all about.
$12.21 on Amazon.com
What useful (non-fiction) books are you reading?