ttfan:
Thank you, I'll start looking there.
Not a technical comment, but a UX comment...
We have had 3 or 4 user panels evaluate features on our sites for a number of years now, to test-drive the sites and to comment / advise on the UX. In almost all evaluations, members of these panels have reported being either disinterested in, or annoyed by, internal "advertising" features such as "you may be interested in..." , "Customers Also Purchased..." and the ever popular (amongst store owners) "sliding banners and carousels.
And the less-relevant the "internal ad", the more it has irritated people. So randomising the product showcase could end up annoying visitors, rather than help them.
We have implemented plugins such as "better together..." by swguy where we are in far better control of internal adverts, and the customers like this. We can customise it product-by-product and while this takes some effort, at least we are not irritating customers with boot-in-the-face irrelevancies.