Rated 4 out of 5 stars
I installed this add-on in Firefox 3.6 and it worked very well. But after I uninstalled it, Firefox couldn't save web pages as before: it didn't create a folder beside the HTML file anymore! Fortunately, I had a backup of the Mozilla folder.
BTW, I'm in Linux (Debian Squeeze) and I'd also installed UnMHT in Firefox.