May not need it for this time of year - a folding Japanese fan - that was priceless waiting in lines - it was hot when we were there. Bandanas, folding hairbrushes/combs, lanyards (we bought ours from ebay and then bought cheap clear plastic id holders at Wal Mart), water bottle with clip, lotion, chap stick, list of dining reservations/itinerary, rain poncho, bandaids/blister care, small tube/stick of sunscreen with clip, Disney gift cards, hmmm - most of these have already been mentioned!
Have a great trip!