Have a look at the Diary module to get an idea of what you will need to build. It has both front and back end forms editing, it should get you pointed in the right direction.
There are many ways to solve this but you're going to have to get your hands dirty.
Thanks for the hint! But if I'm interpreting the code of the Diary module correctly it provides a list of events with corresponding edit-links that lead to a form where you can edit a single event, what is not quite exactly what I'd like to build.
What I am looking for is someting like an editable list. Let's say users should be able to list their biggest wishes. How can I build a form that gets populated with already existing wishes as values in input fields or â€“ if the user is new â€“ shows for example four blank input fields (with the option to insert more by jQuery). Is their a built-in functionality for anything like that or do I have to get my hands really dirty?