A good seat cushion, interesting paperback book, twenty oz. Gatorade(full or empty) thick cheese sandwich on a bagel, bungee cord to attach daypack to tree. Assumeing you will be strapped in, and have normal amount of paraphanelia. If this is a first stand hunt I can get a lot more specific.
Resist the urge to get down at 9AM. No proof but it seems to me that I'll see deer moving around every three hours or so. They aren't travelling far I don't think but they are moving. Another caviat, if you are in or near a bedding area the action will tend towards 8 to 4 if on food sources it will be more toward early and late. I'm in farm country that might make a difference.