Google Hacks: Tips & Tools for Smarter Searching (ISBN 0-596-00447-8) is a book of tips about Google, a popular Internet search engine, by Tara Calishain and Rael Dornfest. The book was published by O'Reilly in February 2003. It covers tips of all kinds, from usage hints for the novice just using Google, to advice for the expert programming the Google Web API. Much of the content provided in the book can also be used for Google Hacking, finding security issues through Google searches. Most programming examples are written in Perl.
The second edition was published in December, 2004 (ISBN 0-596-00857-0).
There was also a third edition published (ISBN 0-596-52706-3).
Theres also Google Hacks Project that you can download http://code.google.com/p/googlehacks/