I've hunted around for a while trying to find a solution to what I believe is a common user interface in the world of data entry but appears to be missing from Drupal.
What I want to be able to do is add/del/edit taxonomy terms for a given content type directly from the Add Content page where the terms show as a multiple select. This is often done with a multi-select box and a simple + - icon next to the multi-select that would bring up an ajax form to manipulate the taxonomy terms and then refresh the multi-select box when the ajax dialog is closed.
For example, say I have a content type for keeping track of books. Fields for Title, ISBN, etc, and a multi-select taxonomy field for book genre (drama, educational, horor, children's, etc) Ideally I want the user to be able to add genre's without having to leave the add book form to do it. I know it can be done with freetagging but then you open up the taxonomy to duplicates and misspellings and other garbage. The multiselect gives a firmer set of choices first and then allows for editing once the user has browsed the list to make sure what they want to add isn't in there already. I would settle for just adding terms from that screen but edit and delete would be nice too.
Taxonomy Other module is ALMOST what I'm looking for, except it doesn't support multi-selects. Are there other modules out there that do this? What about CCK? Any options for using CCK to achieve the same result? I'm using Drupal 6.