Six Apart - ProNet - Make Makes Movable Type Better : Color me blown away by FireFox again... this article from MT ProNet Blog is really only a pointer to something much better, an article called "Make out with FireFox" over at Make: eZine, an O'Reilly Media property.
If you're wondering about the title of this post, read the article, it shows how to install SpellBound, a spell checker, into FireFox to spell check your forms.