A non profit recently opened in my city that promotes reuse of anything that can be used in crafts. I'm cleaning out my sewing room and brought a car load over. Unfortunately (or fortunately) I came home with almost 30 yards of fabric, all for less than $30. Check out their website:
http://austincreativereuse.org/
Maybe your city can start one.
As for cleaning out the sewing room, I took an honest look at all my stuff. Some things I donated I had for 10 years. I figured if I haven't used it in 10 years, I probably will never use it.
I have also donated craft supplies to our local elementary school art department.