I've got 3 young children, and I know how difficult it can be to part with their countless masterpieces. One way I deal with this dilemma is by a simple system of string and clothespins. I have these hanging over their beds and also in the playroom. All you do is tack a piece of twine or yarn to the wall and the artwork can be held up by clothespins – simple, cheap and easy! You can do as many levels as you like, adding to it over the years to cascade down to the floor if you want. The kids can move things around and easily do the hanging themselves.
Here are some other Ideas for storing/saving/using kids art:
How do you deal with and sort through your kids' artwork in your home?