Site maps
Site maps are an important part of your web site. They help users navigate your site but, more importantly, they help search engines find all your pages! There are two options open to you with regards to site maps.
Traditional Site Maps
Normal site maps, with a site map link in the navigation structure, are cheap and simple to create and implement for most small - medium sized sites. Traditional site maps make site navigation easy and help search engines find all pages by allowing them to follow an indexable static text link. This will help you get all your pages ranked and indexed as often as possible.
Google XML Site Map Technology
Google has its own site map technology that is best suited to larger dynamic and search driven sites, although it has benefits for all sites. XML is a data format that allows differnt programs to interact with database formats. Google uses an XML sitemap and site map index file to be able to find 50,000 pages. You can actualy add more than 50,000 pages but this is the maximum for one site map file. Google site maps gives you an account to log into which displays errors, crawler stats and much more useful information.