Ace wraps. Instant ice packs. I've considered packing EMLA and a suture set, the way my son and his cousins carry on at WDW. I pack nearly every thing everyone else has mentioned, and I also pack a pretty extensive first aid kit. This is because I'm a doctor, and pretty much, my family expects me to have all this stuff. Also, I usually have small sample sized packets, which are nice to pack, so I don't need make the choice between 12 tylenol for $1.25 or the bottle of 100 generic for $3.99. I also normally bring my stethoscope and the otoscope (which usually freaks the security inspectors pretty badly--they must think it's weapon. Come to think of it, some of my younger patients do, too).