I know I’ve deleted this bookmark folder myself a couple times…
Just a few weeks ago we showed you how to quickly restore the default Smart Bookmarks that come with the browser, but did you know that it’s also possible to make your own? Thanks to the new bookmarks backend that Mozilla has implemented it’s actually pretty easy for you to create your own Smart Bookmarks once you understand how they work. An extension will inevitably come along that makes this a no-brainer, but it will take you no time to catch on to manually creating them.
The first thing we’re going to do is show you the steps needed to create a new Smart Bookmark, and then we’re going to give you an overview of the query syntax you’ll want to use to take things up a notch.
(CyberNotes: Create Your Own Smart Bookmarks in Firefox 3 via LifeHacker)
Williamo's Blog 
Geek!