I just thought about another couple of items.
Post-it notes. They are great for leaving messages on the cabin door or mirror for cabin mates.
FRS radios are great because your cell phone only works in port.
A Decoration for your cabin door. They all look the same. And, on some ships the cabin number is hard to read.
I can't recall if my first post had it. But the the last few cruises I took a insulated lunch bag. This was great when we went on a shore tour that didn't include a meal. We would order sandwhiches from room service. And, here's where the zip locks come in. Pack it in zip locks, double bag some ice. And we were good to go. I have heard some bring a rolling cooler this would be good too.