Somewhat in the same vein, Colin Walker has built a Webmention Directory on his site that lists all the people (selectively) who have mentioned him in the past. It’s not too different from the purpose of a blogroll.
Similarly Ryan Barrett has built the IndieMap which has a much larger data sample behind it. He unveiled it almost a year ago at IndieWeb Summit 2017.
Maybe we could get the old Technorati alumni in IndieWeb to build something out of this?