Sitemaps and Google Sitemap (beta)
Sitemaps are a guide to the internal linking structure of your site. A sitemap is also spider- friendly and can increase the amount of pages indexed by the major search engines.
Google now offers a way to submit your own sitemap directly to their search
engine. Go here to find out more: google.com/webmasters/sitemaps/login
There's a site out that's a fun parody on SEO, and it's also a great place
to get an XML sitemap generated for free. Check out seo-sucks.com, use
their sitemap generator, and have a few laughs.
Now every site should have a sitemap. It's just 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 links to all your pages, you're 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 sitemap and site.