Another fun target, and what I used to do when I was younger and my eyes were sharper is to get a large cardboard box and stick the handles of plastic spoons in the corregations about every 2 or 3". Then we would set the box up about 50 or so yards and take turns knocking the spoon parts off.
What a blast. There was about 7 or 8 of us and we all had flinters. It was great practice especially when your 'friends' were busting on you while you were trying to aim.