Hi,
some months ago I started programming a Zelda4DX editor. Unfortunately, I soon lost interest in it.
You can have a look at it here: http://cooltoby.co.funpic.de/zelda/dl.php
The reason why I am actually posting is that I am looking for somebody who might be interested to continue this project.
It's written in C# (as you might already have guessed by the name of the archive).
If somebody is interested just post here, so I can send you the source files.
I think if somebody would write a save function, you could already use it for small hacks...
Another interesting idea might be to develop the tool in the some open source environment where everybody could contribute.
Yours,
cooltoby