The full title of this nice not so-little tome reads 'Professional ASP.NET 2.0 Security, Membership, and Role Management', by Stefan Schackow, published by Wrox, Wiley Publishing, Inc. ISBN 978-0-7645-9698-8.
Let's get one thing clear first - Stefan will never get a Nobel prize. This may well be the most boring book I've ever read, it's also full of small typos and minor editorial mistakes. At the same time - it's one of the more readily useful ones too. I read this book cover-to-cover, like I do practically all such books. This might not be the recommended way to get the most fun out of it, however, it's still something that must be done.
Let's get the other thing clear - If you ever think about implementing, extending or otherwise do any kind of real-world application using the ASP.NET 2.0 membership, profile and role providers you need to read this book. The documentation and SDK will not suffice. You may get something that appears to work, but you're missing out on all the little details that will make for really robust and secure code.
Stefan covers with absolutely mind-numbing detail just what actually happens in ASP.NET when a request is authenticated and how authorization uses the identities in all the various scenarios, depending on which IIS version, what kind of impersonation is in effect, what kind of authentication is used etc. This is absolutely essential information, that I've never seen collected like this. I used to work for a leading supplier of content management systems, and the support was constantly plagued by hard-to-debug cases with security related problems. How I wished that I'd read this book then...
After this almost bottom-less dive into the details of the fundament, Stefan continues to cover just how the membership, profile and role providers are architected, how they are intended to be used, interspersed with anectdotes from the development with rationales for various strangenesses that is left in the final product etc. Intermixed are various code samples with how-to recipes to achieve various neat functions by wrapping or extending the providers supplied with ASP.NET.
It's not an inspiring book in the most common sense, but as one manager once told me 20 years ago when he handed me my very own copy of "System 370 Job Control Language" - it's required reading. (It should be noted that I was employed as a Unix/C developer at that time - I still don't know what he was thinking when giving me that book. I did read parts of it though, to my horror... I still have it around to remind me.).
So, if you're working with the security-related providers in ASP.NET 2.0 and don't have one - go get one now! (The Stefan Schackows book, not the JCL one).