I had a look and it seems `no-one` came up with this idea before. Since there is morale, you should be able to make your crewmen happy by letting them party. I'm talkin' wenches and rum kinda party <img src="http://www.piratesahoy.com/forum/style_emoticons/<#EMO_DIR#>/laugh.gif" style="vertical-align:middle" emoid="
:" border="0" alt="laugh.gif" />.
For example, if you have excess rum and food and you are in the middle of the ocean and your crew be restless, let the celebrate. However, if you are in port, you can organize a better one, since you can invite wenches.
You could also let them take shore leave. When you do so, the amount of crew assigned to your ship decreases to about 10% (since someone must be present on board). The longer you let the crew out, the happier they be. But there is a risk. If prior to shore leave, the crew's morale is very very very low, it'll be a chance for them to desert. Similarly, if you let the crew go ashore for a long enough time, some of them won't come back.
You could also introduce loyalty in the game. Based on morale, but more long term. It could be the average morale over the course of the whole game.
Another feature would be the ability to invite governors (provided you are in port) aboard your ship. Depending on how the occasion goes, your reputation could go up or down with the governor. If you are evil, you could also invite a governor, then sail out to seas and ransom him (ofcourse, you'll have to win the governor's trust). Officers and the way they behave, could influence your standing with the governor too, another reason to hire good officers.
Sorry if this doesn't make sense, I'm expanding the idea as I go <img src="http://www.piratesahoy.com/forum/style_emoticons/<#EMO_DIR#>/w00t.gif" style="vertical-align:middle" emoid="
" border="0" alt="w00t.gif" />
EDIT: Got another one. Marines. Basically, they could be like officers (so you could take them ashore with you) but be stronger. They'd be different for each nation and you could get them after getting enough reputation from a certain country.

For example, if you have excess rum and food and you are in the middle of the ocean and your crew be restless, let the celebrate. However, if you are in port, you can organize a better one, since you can invite wenches.
You could also let them take shore leave. When you do so, the amount of crew assigned to your ship decreases to about 10% (since someone must be present on board). The longer you let the crew out, the happier they be. But there is a risk. If prior to shore leave, the crew's morale is very very very low, it'll be a chance for them to desert. Similarly, if you let the crew go ashore for a long enough time, some of them won't come back.
You could also introduce loyalty in the game. Based on morale, but more long term. It could be the average morale over the course of the whole game.
Another feature would be the ability to invite governors (provided you are in port) aboard your ship. Depending on how the occasion goes, your reputation could go up or down with the governor. If you are evil, you could also invite a governor, then sail out to seas and ransom him (ofcourse, you'll have to win the governor's trust). Officers and the way they behave, could influence your standing with the governor too, another reason to hire good officers.
Sorry if this doesn't make sense, I'm expanding the idea as I go <img src="http://www.piratesahoy.com/forum/style_emoticons/<#EMO_DIR#>/w00t.gif" style="vertical-align:middle" emoid="

EDIT: Got another one. Marines. Basically, they could be like officers (so you could take them ashore with you) but be stronger. They'd be different for each nation and you could get them after getting enough reputation from a certain country.