Fortunately, since I live in a two-bedroom apartment, I simply don't have room for a monster stash. And it's not as bad as it sounds. I pretty much can think of every piece of yardage, FQ, and scrap that I own, making it easier to find what I need. I don't even have a designated sewing space. All my sewing supplies - machine, fabric, notions, everything - fit under a twin bed and within a small TV stand. I had to make a rule for myself: if it doesn't fit in those areas, I can't keep it. And I pretty much don't buy fabric unless I need it for something specific. It saves space and lots of money too!
This small space seems to work for me, since I am very disorganized by nature. I LOVE the beautiful sewing rooms so many of you post here, but that's a luxury I just don't see in my near future.