Many SEO professionals have been trying to figure out how to get there search results in Google to display additional links under there main link, some call it extra link listings, some have called it subtopic listings, Matt Cutts, a SEO Blogger calls them Google SiteLinks. Google has given it the official name “sitelinks”.
Look at the sample below, it shows HP results on Google with additional sub category links underneath it, this is what ’sitelinks’ is. Getting your site to show up like this in the search results is apparently based on Google’s sitelinks algorithms, so there isn’t anything at this time that you can put into your site page code to make this happen. We suggest keeping an eye out for news and theories on this feature. You can read more about it at Google’s Webmaster page: