Currently, Google has a "Looking for local results for (generic term)?" zip code field. They also have an automatic local results search using IP matching:
http://www.webpronews.com/topnews/20...c-search-terms
This makes localized content even more relevant. Common localization techniques involve building subpages for all the suburbs/districts of your target area. Common content tactic for real estate, location-specific services, etc.