Like Peter, I periodically see good comments from rep==1 users that are therefore entered as answers. Unfortunately they often get downvoted by people who comment "This is a comment, not an answer." Currently I usually leave a pre-emptive comment saying "not enough rep to leave comments, great comment" to try to avert the down-votes. It would be great if as a high-SO-rep user I could cause these pseudo-comment answers to become comments on my authority, without losing the authorship attribution. For that matter, maybe (optionally) give the new user a few rep points at the same time (after selecting "convert to comment" there needs to be a popup to ask whether it should be a comment on the question or on an existing answer, add a checkbox for "great comment" that gives +10 rep as if it was voted up as an answer, but to prevent abuse this option is only available when the author rep is not enough to leave comments directly).
Ironically, this would have been a great comment to Peter's answer, but here on meta I haven't enough rep.