Add a caption to an image field that allows multiple images OK, the heading isn't the best example of english ever, but I hope you get what I mean...

I've run up against the bug in Drupal where it doesn;t check the length of the title value in an image field (http://drupal.org/node/916446) and I was using that field to store the caption for the image which I was displaying in a div underneath the image.

Is there a way to either allow the title field to hold more information, or even better (semantically especially), create an additional field to hold my caption information?

The reason I don't just create a separate field for caption is that I'm allowing multiple images on the image field and from a content management point of view, I wouldn't easily be able to match up the images to their captions.

I'm sure it's something simple like creating a version of the image.field.inc? Has anyone done it or know how to make this happen?
I believe what you are looking for is the Field Collection module.  It allows you to group fields together and repeat the group many times.  The following article gives a good description of what the module does: Create Multigroups in Drupal 7 using Field Collections

From the Field Collection project page:


  Provides a field-collection field, to which any number of fields can
  be attached.
  
  A field collection is internally represented as an entity, which is
  embedded in the host entity. Thus, if desired field collections may be
  viewed and edited separately too.