If they are marine-grade bungee cords, there are thousands of uses. Do not use those with the plastic coated steel hooks (at least where rust is a concern). Use stainless, nylon or delrin ends. They probably should not be used for long-term storage or storm preparedness - especially when the boat will go unchecked for a while.
I make my own and use them for many things - mostly to hold things while underway (especially racing). I generally release them when not aboard.