Make a simple doll swing out of a cardboard box for a child to play with. Hang it from a door frame or outdoors from a tree branch. You could use it for stuffed animals as well. Check out Pretend Play – School to open a pretend doll school.
Bottle Bank via Martha Stewart: transform a used plastic bottle into a cute piggy bank. Could use same idea to made little containers for kids to store their collections too (use bottle with wider opening and don't make slot)