That gives me an idea - what about a bot, that would go through AfD's, identify the "major contributors" (somehow) and, unless they had already commented on the page, drop a short note on their talk page. I would have not objections to that. (Except for the minor sadness of having *even more* bot-created talk page messages, but that's not really an objection... ;-) ).
Yes I think something like that could really help. And if we cut out the garish colours and unnecessary pictures then it won't even be that annoying from the "talk page spam" point of view.