I’ve managed to get an “on this day” feature working, although because I like to be difficult mine is called Posted Today. It’s powered by a plugin by Alan Levine which I slightly hacked, and which I found from this Chris Aldrich post. I think the fix I added to prevent the current “sticky” post on my front page from inappropriately appearing also will prevent a “sticky” post that happens to actually be from the current day from appearing, so it’s not quite yet a settled matter, but it will do for now.