This is based on the AllProds 2.3
I found that I have better luck in search engines with my category pages than individual product pages - probably due to all the alt and title text so I wanted something that listed all categories and subcategories on a page - with keyword loaded links... for spiders, not visitors. Just as the AllProds contribution displays a list, it also creates links for the spiders to follow... links which have keywords within them which are produced from your product info and in my case... produced from your category/subcategory names.
This contribution produces one page with a list of your categories and subcategories. You then link to this page on all possible pages essentially allowing any spider to crawl your site through keyword-loaded links/URLs.
This is my first contribution as I'm a rookie at php, so please be kind. This is based on the AllProds contribution which I also run simulataneously and thank the contributors for!