Rated 4 out of 5 stars
This works better than every other Sticky-Notes addon here. Especially it does not forget the notes when tabs are switched as it sometimes happens with a similar addon.
However there are some bugs:
1. If the browser is restarted the notes will not be shown. You explicitly need to reload the pages.
2. Sometimes the notes get unmovable and you cannot close them, for example on this page if a note is placed at the height of the "Add-ons for Firefox Firefox" - header. Then it is below of the header which is an a (href) tag.
I fixed those bugs as well as some other problems. The fixed version is available here, at the bottom of the page:
Thank you for creating this.