I have just found out about this, due to having been googlewhacked (see reactions to last post). I had never heard of this; for readers similarly ignorant, here is what Wikipedia has to say:
A Googlewhack is a query consisting of two words (with no quote marks) entered into Google’s search page that returns a single result. Googlewhacking is the pastime of finding such a result. A person attempting to find ‘Googlewhacks’ is known as a Googlewhacker.
The game first appeared on the web at the UnBlinking site on 08 January 2001. The person who coined the term “Googlewhacking” was Gary Stock (http://www.googlewhack.com/stock.htm). A person finding a googlewhack can add it to The Whack Stack at googlewhack.com. (Google does not operate this site, although they are aware of it and approve.)
There are a few Googlewhack rules (http://www.googlewhack.com/rules.htm):
No quotes or other punctuation in the search terms.
The words must be linked from the Google result page to answers.com
The found page must be a real article and not a list of words.
A problem/dilemma arises when a person finds a “googlewhack” and subsequently reports it somewhere on the web: the “googlewhack” will no longer be viable, as the page where it is reported will probably be “indexed” by Google, rendering the googlewhack obsolete.
Example: As of March 3, 2005, the search “adieu halitosi” produced only one result:  (http://www.google.com/search?hl=en&lr=&safe=off&client=safari&rls=en-us&q=adieu+halitosi&btnG=Search) (Although it now returns two matches, one of which is this article.) “Adieu halitosi” is not a true googlewhack, though, because “halitosi” does not link to answers.com. However, by virtue of its inclusion in this article, “Ouagadougou pachycephalosaur” is now a googlewhack.
A more detailed history of Googlewhack can be found at the following unblinking.com page, as well as in the Quick Topic message board set up by Gary Stock for discussion of Googlewhacking.
Googlewhacking: The Search for ‘The One’ (http://www.unblinking.com/heh/googlewhack.htm)
The Quick Topic message board set up by Gary Stock for discussing Googlewhack:
Googlewhack: The Next Generation (http://www.quicktopic.com/25/H/qs4HWCvwsmY8M)
All of which suggests that there are people out there with too much time on their hands; as far as I can see, the googlewhacker perceives it as somehow interesting in itself that malfeasance and celeriacs can appear in the same blog. But surely this is to do, essentially, with having a large vocabulary, and enjoying using it? I have to say that I have been googlewhacking myself lately, quite unaware that I was doing any such thing. I have been trying to track the sources of a complicated treatise by a particularly rebarbative 17th century theologian called John Owen, and have called Google to my aid — an astonishing amount of Latin is now floating about in cyberspace and typing a two or three word phrases in Latin into Google has enabled me to tick off, for example, classical playwrights and poets with contemptuous ease. But theologians are rather poorly represented, so I will have to resort to antique methods, viz., visiting a library.