The National Security Agency just declassified a hefty 643-page research manual called Untangling the Web: A Guide to Internet Research (PDF) that, at least at first, doesn't appear all that interesting. That is, except for one section on page 73: "Google Hacking."
Well, you could type the following advanced search into Google — "filetype:xls site:za confidential" — to uncover a trove of seemingly private spreadsheets. How about an Excel file containing Russian passwords? Try: "filetype:xls site:ru login."
These are just two examples of the numerous private files that are inadvertently uploaded to the Internet, and can be accessed if you know the right Google search terms.
Here are a few more:
Pretty neat, huh? Declassified information being what it is, though, some of the search tips can appear a little dated.
And even if keyboard espionage isn't really your thing, the document contains a number of practical tips anyone can use to become a better Googler:
* Adding a tilde (~) immediately before a term will search for its synonyms. For example: "Scary ~animals" will also search for "scary creatures," etc.
* Repeating a word will help you find more relevant hits. For example a search for "java coffee coffee coffee" will cut down on the results about the programming language.
* You can use Google wildcard (*) to replace a term in a query if you don't know exactly what you're searching for. For example: "Sacramento is the * of California."