Rated 5 out of 5 stars
I'm surprised I haven't discovered this add-on until now. This is the best one I've found in a long time. I read fanfiction and bookmark ones I like based on what fandom they're in, so it's incredibly convenient to put it in the right folder with this rather than having to scroll through the 'edit this bookmark' dialogue to find the folder it belongs in, and the number of options is it gives you is great.
I've heard that it's broken in Firefox 23, but that's okay since I stopped updating when 22 broke a few addons that were pretty much deal breakers.