I'm trying to create a site for an automotive site. The first pull-down is year, then make, then model, then fuel type. Each one is context sensitive based on the last selection. See "Search by Model" on [url removed, login to view] for a sample. My cart is designed in Opencart. There are two commercial modules available on Opencart's site but they both can't handle lots of categories (70,000+) because they work by flatfile format. I'm told this needs to be done in AJAX so that it pulls in the categories from the DB in realtime. Currently, I have one of those modules installed and when I access the site, it starts writing THOUSANDS of little cache files in the system/cache folder and it never finishes so the site never is shown on the browser.