Instead of asking what Ambergris Caye needs. Shouldn't you ask yourself what do I know how to do that can benefit the community and myself. Do you know how many people come down here to start a business that they have never tried before. I am sorry but that is just plain stupid. That is why so many restaurants, bars and stores close down. Don't expect to come down here and magically be able to open up any kind of business if you don't have experience in it. You will have to train your staff and a lot of time you will be the one doing all the work.
Read some of the older posts on this board regarding moving down here...you do need to know what you are getting yourselves into.
Good luck!