Rated 4 out of 5 stars

I love this easy way to tag my bookmarks! Just 2 features more, and for me it's worth a five star rating:

- customizable icons (changing the types of icons, which will be displayed/suggested) and
- a "View tagmark tags"-button inside the statusbar or the navigationbar of Firefox (or another proposal: toggling a tag with the left mouse button - like it is - and showing all sites of a tag by clicking it with the right mouse button)

I'm looking forward to seeing the implementation of your ideas! Thx for this great add on!