Google ended 2011 with just under two thirds of market share for search queries in the United States.  In other words, of the approximately 18 billion explicit core searches, Google accounted for about 12 billion.  Google offers options for taking advantacge of placement on their pages.  Marketing By Nature recommends Google Analytics as an easy free first step.  However, data released early 2012 shows that specifically targeted advertising ups clicks substantially.  This table indicates how, even when a business shows up in the number one organic search result position, 50% of the clicks they got on paid ads are not replaced by clicks on organic search results when the ads don't appear.  Even more significant, the study found that the number rises to 82%  when the organic search result is ranked 2-4 and almost 100%  when the brand's organic result was below five. 

Conclusion:  Seriously consider the minimal cost of Google Ad placement to up clicks and views of your site and return on investment.