Check out the Google Sitemap Generator (http://googlewebmastercentral.blogspot.com/2009/01/new-google-sitemap-generator-for-your.html). Using this application first is a great way to get started. The application and some of the support materials will help you understand your sitemap XML file, can help you generate it yourself or (at a minimum) will teach you how to build your own generator. Building it yourself is the most recommended, but most expensive, path to follow.
The only crucial issue for a tool like this is the SEO friendliness of your URLs and your site in general. If your site is out-of-date, poorly built, and not generally available via a search engine, then this sort of tool won’t really help you. You are better off re-factoring your site for SEO friendliness before generating a site map.
-=John

You must log in to post a comment.