Anything that will be seen and used on a decently regular basis. This lets the others see it in action. OR anything that you wouldn't mind having but refuse to pay for like a dodger.
Matching foul and fair weather gear with your ship's name for the honeymoon cruise.
Gift cards as mentioned above are always good these days.
Galley gear. Plates with the ship's name etc...
Any Weems and Plath stuff as mentioned above. Too expensive to buy yourself