I built my three hens a little addition to the chicken run to use up some of the scrap hard wire cloth and lumber I had floating around in the shed. It's a little 3'x3' pen that I can open up for their snacking pleasure.
I'll let them have access to it for an hour or so a day, once the grass is filled in and jungle-y.
My hope with this addition is to increase the nutritional value and production of the eggs that my hens provide. I have no idea if it'll help or not, but I bet they'll have a blast destroying it. :)