Just this past weekend I went to Michael's and finally picked up a couple of the Recollections brand 12x12 storage cubes for hanging folders. There are of course a few issues with this system. The tracks are just plastic sliding against particleboard and are not very strong- this will probably break down with use as the paper gets pretty heavy when you pile it in there. There is also no stopper on the tracks, which means that it is very easy for your paper collection to land on your foot (ouch) or on curious little ones like I have. DH installed some sliding door locks (similar to the ones on the doors in bathroom stalls) at the back of the inner part to serve as stoppers, and if I do want to remove the whole rack of paper I can just slide the locks open.
I bought two units and stacked one on top of the other, as you're supposed to be able to do. It's absolutely necessary to secure the units to one another with metal brackets and screws, and also to the wall behind the units. There is a lot of weight carried by the drawer when it's open, and it automatically tips the whole setup forward if you don't do this. My DH fixed the top unit not only to the wall behind, but to my desk and the bookcase on either side. Now I can open the drawers without it falling over.
The other thing that irks me is how scarce the 12x12 folders are to fit inside. Four folders were included with each unit, and Michael's had four packages of six folders each- I bought them all but would like to have about a hundred of these things! So instead of having one colour per folder, nicely labelled, I have had to put half my reds in one, half in another, and similarly with all the other colours. And you can't use standard file folder labels on the tops of these either- there is not enough room between the top of the folders and the top of the unit for anything more than 3/8".
So, for all that you might wonder why the heck I'm keeping them. Well, simply because there really is nothing else I can find in Canada to fit 12x12 cardstock in hanging files. I am VERY happy though to not have to stand under a downpour of paper every time I pull a stack of cs off my shelf above my desk, which is where I had been keeping them! This will work for me until the unit breaks down, at which point I might ask DH to construct a better unit!