Google’s index of web pages is generally regarded as the largest of all the major search engines. This means that for most searches, it’s not uncommon for Google to report millions or even tens of millions of pages containing your search terms.

On the opposite end of the spectrum, however, there are combinations of keywords that return only one single result on Google. Web entrepreneur, online commentator and gadfly Gary Stock is obsessed with finding these combinations. So much so that he’s created a game, complete with rules, that he calls “Googlewhacking.” In some respects, it’s like trying to find the next prime number.
More About Googlewhacking Here .

The complete rules here