Ignore list would make for a good native feature, e.g. just auto-collapse comments by people from the list. Along the same lines, a watch/friend list would be

Ignore list would make for a good native feature, e.g. just auto-collapse comments by people from the list. Along the same lines, a watch/friend list would be handy too - highlight comments from selected people in some subtle way, so to make it easier to spot them. ... though I think dang would easily produce good arguments against both of these :)