https://www.google.com/webmasters/tools/

Once you have a published website online, Google webmaster tools lets you verify important information on your site. Google-webmaster-tool will notify you through its dashboard if there is dead-links on your site, or if there's any technical navigation problem on your site. It also shows you for which keywords you site shows up on the google search results page.

Sitemaps & Discoverability
Unlike a traditional html, user-accessible sit map, a sitemap.xml file lets google and other services learn the structure of your site. If Google-searhc can understand the structure of your site, it will be able to index it's content more easily and direct users to the right pages.

While it's fairly simple to write a sitemap.xml file manually, many tools are avaialble to you to create one directly. Google suggest a variety of tools that might help you create sitemap.xml files.



Blog and discussion groups around Google webmaster tools: Google Webmaster Tools