ediff-{tar,zip}-files?

[Skip Montanaro]

Is there an add-on for ediff which allows it to treat archives like
tarfiles or zip archives as if they were directories? I suspect Emacs
has most of the groundwork already laid, as if you visit such a file
it brings up a listing of said archive. Kind of smash that
functionality together with ediff-directories? I checked the package
manager, did some web searching, and poked around the EmacsWiki a bit,
but found nothing obvious.

I can't be the only person who has ever needed this. In fact, outside
of Emacs, I've written a couple versions of "tar diff" in the past
(expand both archives into tmp dirs, run ediff -ru | less on them,
remove on exit). While that's workable, the ediff interface would be
so much nicer than just picking through diff -u output manually.

Thx,

Skip