I have added a list of manufactures (manufacturer is a regular, filterable attribute) to every category dropdown in my navigation. I populated the list using the exact method described by Jasper here (http://stackoverflow.com/questions/3157799/magento-get-filterable-attributes-by-category)
This method works on all pages EXCEPT a page that is filtered by manufacturer already. I want this list in the dropdown to show up regardless of the page I'm on. I suspect that the "currently shopping by" block is removing the Manufacturer filter somehow. Any ideas about how to make the manufacturer list remain in the dropdowns?