Rated 5 out of 5 stars

I like it, but one suggestion would be to make the dropdown notifications specific to the tab they were generated from - using something like gBrowser.getNotificationBox(gBrowser.getBrowserForDocument(aDocument)); -- It's a little annoying getting the notifications when I open a bunch of new tabs (when I'm not looking at those tabs yet)

This review is for a previous version of the add-on (1.8.1).