I'm using drupal 6 with CCK and Views2 installed (and looking forward to Panels when its in shape for a production site).
I got an idea for managing "letters" on the site, partly inspired by some documentation on using Node Comment and Five Star to create a "review" content type (http://drupal.org/node/234681). (I don't want to go this route, however, because I don't want to disable core comments, as node comment seems to require, and I also want to use Node Queue to create a list of featured letters, and I don't think Node Queue supports comments with core comment module.)
Here's what I would like for a letters section: I would like users to have the ability simply to visit a "letters" link on my site in order to post a letter to the editor, but I would also like to have a link appear at the end of every story which would also launch the letters feature, but in doing so it would also create a re: tag in the letter that would link back to the specific story from which the user launched the letters content.
In other words, if a user is posting a letter about a specific article, clicking the write a letter about this story link that appears at the end of the article would automatically reference the original article, so we don't have to count on users to do this themselves. That way, when we get a "your story really irritates me" letter, we'd know which letter irritates the reader.
I'm hesitant to use comments to do this because I want the letters to appear separately from the originating story (though perhaps we would use a view to create a list of links to letters referencing any particular story), and because I want to use comments in other places on the site. Readers would be able to view all letters, but our editors would be able to mark particular letters and have them appear more prominently on the site.
Anyhow, I'm at initial stages of figuring out how to do this. I know I can very easily create a letters content type using CCK. But I'm not sure how to create a link for each story that would automatically create a link in the letter back to the originating story.
So, I ask your suggestions. Is this something I should pursue in this way? Or is it a better plan just to use comments and views to do this? One real limitation to this approach is that I would likely use Node Queue to create the list of featured letters, and I don't think this would be possible with comments, even though Views now supports comments.
Any feedback on this idea? What would people suggest?

Comments
Nodeformpopup + Node form template
A neat solution would be to create a new letters content type, just as you suggest - and use a popup window from a story to create a new letter. With the help of Nodeformpopup and Node form template you can have fields automatically filled in, for example with title and url to the source page.
I'm using a solution similar to this to add possibe news stories to an internal website - just by marking some text and clicking a bookmark I get a new node with header, link and selected text in the body. You'll find a writeup here. Instead of using bookmarks, you should be using a link, but I guess that would be easy to arrange.
By using Formfilter you can hide the link field, eliminating the risk of someone accidentally changing it. (This can of course be done with theming instead.)
None of the mentioned modules are available for Drupal 6, which is a problem. But I don't think they will be difficult to port.
I hope this gives you some useful ideas!
//Johan Falk, Sweden
blog module's implementation of hook_form
Have a look at blog module's implementation of hook_form. Aggregator module provides links that pass the item ID (iid) on the URL, which the blog form picks up and quotes in the body of the blog post. It's slightly clumsy and specific to aggregator, but it's not hard to change this to node ids.