Using a configuration management tool is one of the most impactful ways to have dramatically faster, cheaper, more stable systems.
If you're not using one already, this book will give you a good taste of each of the most popular tools.
If you're using a tool and aren't completely happy with it, then this will give you a good introduction to the other available tools.
Either way, this book can save you weeks of effort and research. If you value your time, it's a great investment.
(Status: No longer a book - now a training program at High Velocity Ops)
In my contracting career, I've run development and operations projects for billion dollar companies as well as many smaller businesses and startups.
Nearly always, there are opportunities to speed up their projects and reduce their systems costs by a factor of 10X or more. That's an insane amount if you think about it.
If you want to run circles around your competitors, this book will give you the tools to speed by them.