I don't know it this has been brought up before but me and several others who I have spoken to would think that the option to design sails and flags would be a nice little addition to the game. Maybe even Rare could create a little community market for them where players can put up their designs and sell them for gold. There are some incredibly talented people out there and I bet we could see some fantastic and unique designs.
Or have a mini update/quest "The Lost Sails" where players venture out on various quests to find designs for sails where they then have to take the designs back to the shipwright to get them made.