I think the URL-autocompletion in firefox works great, except for one problem: On many websites I like that firefox learns the full url and autocompletes it. But on some websites, firefox learned the wrong url-parameters or url-parameters don't make much sense on this site. In this cases I would like beeing able to disable full-url autocompletion for specific websites, so only the host and protocol part of the URL is autocompleted for this websites.
One suggestion would be to adding this option to the context menu of the search bar.