I used to have piles and did the same thing. I bought some of the reusable cloth/mesh grocery bags and put each project in a separate bag. They are cheap enough at $1.00 or so, and I don't have to worry about the fabric not being able to "breathe." (I heard that storing in closed plastic bags wasn't a good idea...)
I lay the bags back on the shelf, but I suppose you could hang them if you want.