Firefox antisocial bookmark tagging.
Version:TagSifter provides a different way of looking at your bookmarks: they're "tagged" by the folders that contain them. Folders in different parts of the bookmarks hierarchy with the same name represent the same tag. TagSifter therefore lets you manage your bookmarks in a non-hierarchical way.
Operating System: Mac OS X
When you add a bookmark, instead of choosing the one folder to put it in, you choose the tags you want to give it and TagSifter files the bookmark for you.
When you want to recall a bookmark, instead of hunting for it through folders and subfolders, you browse by tags, using them like a sieve to filter out unwanted bookmarks.