Here is just a blog where Seth Godin Explain how he was tracking the spreading of idea with one article from new york times. In the article, he said that once he read the article from NYT, he just went to google for searching for the old book cited in the article. Like Seth millions and millions of people are doing the same thing. Reading an article and searching on google anything that was said in the article. The conclusion is that news drives search. If you can track news and get the keywords into news that are likely to be searched you can have a good way to target the reader of this news.