boy that's a big mess (i think). this is the flickr model. flickr uses two container types that are basically the same thing, "collections" and "sets" and you can shuffle between them at will. to some it's needlessly confusing while to others it allows that extra level of organizational ability. personally i like it but never saw the parallel to coin collections - now that you're bringing it up it must mean that it'd be desirable to have this ability here too!
not sure how much of a programming overhaul this would mean but i can start the lengthy process of getting the programmers to bounce some ideas and let's see what happens.
we're up to four programmers now by the way and making progress on a couple of new tools i think all members will like. i'm fairly confident i'll have something before month's end :-)