http://mozillalinks.blogspot.com/2006/05/bon-echo-aka-firefox-2-alpha-2-review.html
Inline spell checking! :)
You should also grab this extension (https://addons.mozilla.org/firefox/1951/) that merges the progress and address bars, Ive been using it for a few months now and itll hopefully appear in later revisions of FF 2.0 . :)