For many reasons often webmasters tend to optimize their site for Geographic Locations. Lets say you are selling candy online for USA, and you don't ship anywhere else. Its very likely that you would want to optimize your site for that geographic location. 

Why you wanna optimize for geographical location?

First of all to get higher ranking on search results. If you specify your site for a location your site will will be the preferred one over the ones that are not geographically targeted. 

Another reason could be you just don't wanna do business with other locations. 

So how do you optimize a site for geographic location?

Here are few tips that will hep you rank geographically.

- Include location name in your title tag ( e.g. Free Classified Ads Boston USA )

- Include physical address in your contact us page. Specify street address, city , state/province, zip code, and country on contact page.

- Set geographical location in Google webmaster central. If webmaster central for other search engines allow you specify geographical location, set the location there as well.

- Add your site to Google local business center. Url is http://www.google.com/local/add/

- Add your site to Yahoo local business. Url is http://local.yahoo.com/

- Integrate google map location in ur contact us page. Here is a good tutorial you could look at http://www.developer.com/java/web/article.php/10935_3528381

- Get link from local sites. Local classified ad posting is an option for that. http://www.webcosmo.com is one site to mention.

And you should move up the rankings for geo-targetted sites.