[quote name=\'DrBear\' date=\'Jan 24 2004, 08:59 AM\'] OK...would Peter Marshall's visit to Bergeron's Squares count? [/quote]
I see no reason why it wouldn't - actually it fits the picture even more than some of the ones we've mentioned.
I would actually be more apt to classify Jim Peck as "substitute host", if you could call "substitute" and "filling in" the same thing - I'm pretty sure the beginning of the show, Johnny G. introduced him as "filling in for Jack Barry, Jim Peck!".
Peter Marshall, since he was only on one episode, would definitely be a guest host, as he was a guest to H2.