You should be using sitemaps on your site to aid and assist spiders that crawl your site. Its is really in your best interest.

1. Read about sitemaps:
http://articles.techrepublic.com.com/…

2. See the new standard being pushed:
http://www.sitemaps.org/

3. Create a Google Webmaster Account and get started:
http://www.google.com/webmasters/

Check out these posts too:

  1. Create Google sitemaps online
  2. Google releases Code Search sitemaps
  3. Google Sitemaps FAQ
  4. Google Webmaster Central launches
  5. Google extends support for determining links to your site
  6. Webmaster tools from search engines gives valuable information
  7. How to submit your website to the major search engines