Mozilla's personal toolbar allows you use folders of bookmarks pretty well.
The personal toolbar is the thing in that shot that goes "Cellar Daily Blogs Weekly..."
The Cellar is a direct link to here, and of course everyone should have that first on their toolbar. From there, you see folders, and in those folders are bookmarks (and in a few cases, more folders of bookmarks).
Setting it up this way, I have a place for two kinds of links that I visit every day, in the "daily" and "blogs" folders; and the rest of the toolbar is just an attempt to categorize stuff that I know I will visit again.
You can drag and drop a link from the location bar right into any of these folders. You manage it all via the standard bookmarks "manage bookmarks".