There is plenty of evidence indicating web searches are a leading indicator of economic trends (http://www.huffingtonpost.com/2009/07/17/summers-economy-has-moved_0_n_237684.html and http://www.washingtonpost.com/wp-dyn/content/article/2009/09/11/AR2009091103771.html?hpid=topnews). There are even some boffins who make money on the conspiracy circuit with the "Web Bot Project".
Now Google has unleashed a fascinating economic prediction tool: Google Domestic Trends.
And as Fast Company mentions, this could be quite useful to the investor looking to profit from future trends.
GoogleBlog's official announcement