Sitemaps are a value internal linking structure to your site. It is very spider friendly and can increase the amount of pages indexed by the major search engines.

Google now offers a way to submit your own site map directly to their search engine. Go here to find out more: google.com/webmasters/sitemaps/login

There is a site out that is a fun parody on SEO, and it's also a great place to get a XML site map generated for free.

Now every site should have a sitemap. This should just be a page that has all the urls on the site.

Either way, if you don't have links on your site to a sitemap or a page with all your links your missing out on a lot of search engine activity.

Learn how you can tell when the search engines spider your site map and site.