There are a number of companies that offer Honeymoon Registries where guests can buy you meals and activities (tours, shows, spa treatments, etc.) at your honeymoon destination. Each program is different so I suggest doing some research on several companies before deciding which one to register at.
There was one bride who told me that the site she registered at looks like guests are gifting you specific things to do while on your honeymoon, such as dinners, massages, sightseeing tours, but in reality the site would send the couple cash, less a 10% fee. I do not recommend this type of program because it is deceitful to your guests.
If you do register at a honeymoon registry company I suggest you also register at a traditional retailer so guests who would like to buy you something for your home have that option. You will find that guests of your parents’ and grandparents’ age may go this route.