Great work guys! not something I would have originally seen myself using, but having now tested it out I can see this replacing my bookmarks bar! Search could do with improving but I'm sure you'll sort that ;) any chance of viewing bookmarks that are the union or intersection of two tags/folders? I think that is something that would change how I organised my bookmarks, but would be useful to me personally (and I'd bet a whole bunch of other users).
Union/intersection could be quite useful for me too, FWIW. Might confuse the whole tag selection UI side of things (with requiring a 'clear selection' or 'clear this selected tag' type functionality too—just my $0.02.
