cck Nodereference for files I am trying to create a node that has a single file attachment (using CCK filefield), and be able to reference that file by other nodes (possibly more than one node).  

The application is such that there's a "forms library" that will have various documents refer to forms.

I have looked at FileField Sources, but I'm not clear if I change a file in node A, if the attached file in node B will reflect that change.

Additionally, we're finding related nodes based on taxonomy terms (http://drupal.org/project/relevant_content), so it would be nice if I could refer to the node, but by clicking on the link to the node (via the node reference), the file opens.

I've looked at Custom Formatters (http://drupal.org/project/custom_formatters) and Formatters 4 Node Reference (http://drupal.org/project/formatters4nodereference) as suggested by Attaching existing server files to filefield, but I don't seem to "get" the two modules, and neither of them are flush with documentation.

Is there a module for this, or am I looking at writing something?
You don't want FileField Sources, you want to use a Node Reference field on the node you want to reference the file on, and you want to change the display of the node reference field with either a Custom Formatter (that you'd need to write yourself) or a standard FileField via the Formatters 4 Node Reference field module.

To change the display of the Node Reference you would want to goto the Display Fields page on your Content Type and select the new Formatter from the dropdown.

A brief demo of what you could potentially do for this sort of system can be seen at: http://www.youtube.com/watch?v=qBXoN25guic