Untangling the Web is the National Security Agency's once-classified guide to finding information on the internet. From the basic to the advanced, this 650-page book offers a fascinating look at tricks the "real spies" use to uncover hidden (and not-so-hidden) information online.

Chapters include:

Google hacks
Metasearch sites
Custom search engines
Maps & mapping
Uncovering the invisible internet
Beyond search engines: Specialized research tools
Email lookups
Finding people
Researching companies
A plain english guide to interworking
Internet toolkits
Finding ISPs
Cybergeography
Internet privacy and security

....and over a hundred more chapters.

This quote from the authors hints at the investigative power of the techniques this book teaches:

"Nothing I am going to describe to you is illegal, nor does it in any way involve accessing unauthorized data, [...but] involves using publicly available search engines to access publicly available information that almost certainly was not intended for public distribution."

From search strings that will reveal secret documents from South Africa ("filetype: xls site: za confidential") to tracking down tables of Russian passwords ("filetype: xls site: ru login"), this is both an instructive and voyeuristic look at how the most powerful spy agency in the world uses Google.