Rated 5 out of 5 stars
This is the better than Stealther for hiding a browsing session. Stealther will nuke ALL of your browsing history, while Distrust will just hide your browsing for one session.
0.8.1, the version compatible with FF3 is no longer on his site, but I was able to find it here:
Don't worry about the Italian, the extension itself will be in English.