A silly string arena! Use the hay to make an arena with a couples bales in the middle then give kids a can of silly string to shoot at each other until it is empty. The kids have a blast, the parents enjoy watching and occasionally get hit as well.
Each October we have what we call a "Fall Festival". Our PTO President has done a fantastic job in previous years with this project. She hires a local farm that brings in a small petting zoo (rabbits, goats, chicks, sheep and baby pigs) - each child gets to pick a pumpkin from our pumpkin patch - we have a table set up where each child gets to pick a bag (purchased from Oriental Trading) to hold all of their goodies, we have a cookies and juice station, a tatoo station, a hay maze with great dads that scare the life out of the kids (we do a scary maze and a regular one for the kids that don't want to be scared) - we do a find a pencil in the haystack, a candy sandy station and this year we added a guess how many pieces of candy in the jar station.
Does anyone have any other ideas that we may be missing that we could add this year?