Rated 5 out of 5 stars

IMHO, this fixes Firefox behavior to what should have been the default, to NOT remember accepting a questionable certificate unless the user specifically chooses to remember. Very simple function, performed with no noticeable side effects for the two years I've used XULernia.

It would be nice to have ability to also set these config options as well, to streamline the cert acceptance for experienced users who frequently need to use certs that aren't from trusted roots, but at least there is a way for users to set them manually:
browser.ssl_override_behavior = 2
browser.xul.error_pages.expert_bad_cert = true

This review is for a previous version of the add-on (2011010201).