I'd like to have the ability to add a caption to each attached file (after the upload, but part of the post form) that would be shown instead of the "filename, size, downloads" default caption.

If you are uploading a set of photos, it would be nice to be able to describe each photo individually (so the caption shows when viewing in the lightbox).

The caption input box could appear between the filename and "Add to post" link when the uploaded attachment appears in the Attachments list. If the poster doesn't enter anything for a caption, then the default "filename, size, downloads" would be used.

+1 sounds like a good idea to me. Caption and comments would be nice to show in the lightbox view. Users would like the option to add captions and descriptions (I think).