Nothing spectacular, basically existing functionality Rated 2 out of 5 stars

This is just a GUI for the "network.automatic-ntlm-auth.trusted-uris" value of the "about:config" page... if anything, it makes adding the URL's more difficult, since you can't add them comma-separated or without "http" prefix. For this to be actually useful a content menu like "Add this URL" or automatic/wildcard addition of an HTTP Auth protected pages (not a good idea from security perspective) would need to be added; as of right now this could very well be replaced with a link to above configuration value.

This review is for a previous version of the add-on (1.2.0.1-signed).