Hi tugbucket,
I was actually interested in WooCommere’s product attribute, which is a type of custom taxonomy. I forgot where I read it, but Woo seemed to automatically register a product attributes as “pa_xxxx” as the taxonomies slug (xxxx is the slug under the product attribute configuration page).
Hence, I simply used pa_xxxx as the taxonomy value in your shortcode and it worked.
BTW, to properly show the attribute archive, one need to follow the instruction at the end of the following page:
https://docs.woothemes.com/document/using-custom-attributes-in-menus/