The website I am working on has a few hundred PDFs in it. I don't think I have ever seen any of them come back in a search but there are linked to directly from out site. They are also full of keywords because they are product documents.

Is there anything special we need to do to get Google or other search engines to crawl them?

Is there any hard and fast rules for making PDFs to help Google like them more? For instance should I run them through ghostscript to clean up broken PDF tags that Adobe creates during generation?