Typically many sites could improve their indexability by having a static home page or by minimizing the number of variables used in their dynamic databases. Many search engines also have problems following java. A good way to tell if a search engine can crawl your page is by using a Lynx viewer.

The best ways around this are to create a static home page and to have a static site map which links into most of your primary pages.
Some sites designers think about the search engines after they are built. This is part of the reason directories like GoGuides are far more popular than Illumirate. A huge part of the value of a directory listing is the value of the spiderable text link. Each additional page in the index is one additional page that can be found in the search results.

Some good general tips

• Use a static page as the home page if possible

• If you use dynamic pages do not force feed the spiders cookies.
• If you use dynamic pages keep the id # at 10 or less digets per string.
• If you use dynamic pages use 3 or less variables if possible.
• Use a site map to give search engines a second path through your site.

An additional bonus with owning a site map is that it can provide keyword dense anchor text links into pages when site design prevents some of the links from being optimized through the regular navigation.