Others have mentioned pull out shelving behind your closet doors, but my suggestion is not shelving but deep drawers. A friend had drawers built into an attic space and from the room side it looked just like a chest of drawers. I had my hubby do that in my kitchen closet, I could only have one drawer plus shelves( made a pantry), but that one drawer sure holds a lot! It's about 10 inches tall by 36deep and wide. He bought really heavy metal drawer slides. You can only go "up" so high or you won"T be able to get in the drawer when you pull it out, but now you can even buy tracks for cabinets that let you have pullout/drop down space.