Knowing more about your users makes it easier to build products they’ll want to use, and gives you a great shot at anticipating their search behaviour. Google Analytics and Webmaster Tools already provide some of this information. Now if only there was a centralised source of information on people, including age and gender, with a geographical breakdown and data on competing local businesses. Wouldn’t that be handy?
As Harris Schachter points out on the SEOMoz blog, this information already exits in a usable, searchable format, at least for the United States: the US Census. Read his Guide to US Census Data for Local SEO and get ready to reboot your local SEO efforts.