Trying to build a "Mad Lib"-like content type

I have Drupal 5 and the CCK and Views modules, and am trying to build a Mad-Lib style fill-in-the-blanks content type. :)

There are a number of 'templates' to choose from, of the approximate form:
Yesterday, %person% went to %place% to see the %animal%
(choice of % tag format is arbitrary and alterable)

I want a drop-down list of choices for each different %tag%, but sharing the same lists for all templates (so %animal% always refers to the same list of animals, etc). I'm moderately competent at PHP programming and have coded a little for Drupal before, but not with the CCK.

So far I've got the templates as a custom content type, and can select the template nodes via the nodereference field type from the CCK - but I'm not really sure how the best way would be to go about offering selections for the 'blanks', or to actually store them in the DB. All the lists need to be relatively easy to edit, and different templates will not have the same tags present, so the form kinda needs to be dynamic to present only the relevant choices for the chosen template.

I'm fumbling my way through this on my own, but if anyone who is more familiar with how things are 'done' in Drupal and the CCK can offer suggestions for how I might best go about this, it would be much appreciated. I don't expect any code, just vague design thoughts :)

Thanks in advance, folks of this fine community.