Sitemaps and Google Sitemap
Sitemaps are a value internal linking structure to your site. It also 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. Go check out seo-sucks.com and use thier site map generator and have a few laughs.
Now every site should have a sitemap. This should just be a page that has all the urls on the site. Some sites like this one, use the menu as a sitemap as well.
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.
I would suggest learning a little more about your server stats by visiting a site like track-it-now, to find out how you can tell when the search engines have spidered your site map and site.