>> <snip> write something once and sell it a zillion times. Of course first you need the idea and the time to do it....
>
>Unless you give your customer all rights to the app you built for him, there is notthing stopping you from selling a zillion copies of that app. I know a developer that started this way and is now selling a fraction of a zillion copies.

Thus far the customer has retained the rights for the apps I've built or worked on.