There's a Japanese clothing and housewares store called Muji that sells nice stacking drawers in various sizes. I store all of my parts collection in ziplock bags, in these drawers. I have 10 now (23h x 33w x 44d, cm) , and am thinking of getting a couple more. Categories are brakes, cranks and chainrings, derailers, saddles and so on. I set up a spreadsheet inventory for them. Bars hang out on top of them, Frames are on a bed that's not being used. Wheels, well, they're sort of in a jumble.