Rated 5 out of 5 stars
It used to be a major commodity in my browser, has stopped working in Firefox 3.0.7. Please update.
P.S.- for everyone interested: after a google search I came across an extension called FoxNotes. It turned out to be a direct continuation of QuickNote, integrating into the browser the same way. It manages up to ten note-tabs, and has more sensible customization.
So the update exists, it only isn't publicized on this site - rather inexplicably.