NAC Geographic Products (NACGEO) has introduced a meta tag called the Natural Area Coding system or NAC for short. Essentially it is a coded system that will allow you to identify the geographical location related to your website with a standardized meta tag.
The system is quite complex, but there are already generators that will provide you with the proper code once you input the desired address. It also has not been widely adopted yet, or officially recognized by any of the large search engines, so it has some major hurdles to overcome.
With 25% of searches consisting of surfers looking for businesses “near my home or work” (source: Search Engine Watch ) This meta tag could come in handy, though if it is Widely adopted I am not sure how search engines would avoid the page spammers that plague other meta tags.
