cruise excursions for the wedding registry??

So I have heard and read in all the bridal magazines that people are registering for their honeymoon cruise excursions. My fiance and I are 100% on board with this, but we aren't sure how to do it. I called Norwegian Cruise lines to see if they could help me, this is the cruise line we are taking, but they said that they don't provide that service. There best advice was to just look up what we wanted to tell everyone. Well that was helpful right??? (that was said in a sarcastic tone if you couldn't tell) Has anyone found a site that can do this for you. One that is reliable and isn't going to steal your family's money?? I really don't want to just tell people what we want and have them give money. HELP!