If you enjoy great views, a free ride and don't mind freezing your buns off than a ride on the Staten Island Ferry is your ticket. It is easy to board, you don't need a ticket and since you walk on it is easy to ride over and catch the return ride back. Living in a region where there are a lot of ferries and they can be pricy, it is hard to believe that such a great ride is 100% free.
Cruising past the Statue of Liberty particularly at night is an awesome sight.