Most of my web application have some kind of hierarchical structure in their models. It gives my users the ability to categorize their data in a pleasant way. The only problem is that its hard to create a user interface for editing these hierarchies. I made a prototype which adds nested set support to the symfony (1.2) generator. This extension allows for full drag&drop nested set support! See for yourself http://nested.redotheoffice.com
A short snippet to visually dump the Doctrine-data-objects to your screen. It helps me with debugging the recursive data-structures Doctrine produces.
This tutorial describes how to create one sfForm which edits an object, edits related objects and allows you to add or remove related objects:
I regularly need a form to edit more than one object at once. To explain this more clearly: imagine an Author - Book relation. Doctrine builds you standard forms for the Author and Book objects, but you can only use them separate. Why not combine the forms using code like in the following lines?
$form = [...]