Does XF or an add-on have this? If not, this makes a neat little add-0n. I have it on my existing forum- this sends me an email when a member changes certain profile fields - in the case of XF, it might be home page and about you. With 20,000+ members I only get a couple emails per week so it doesn't get in the way. But it's an easy way to catch the sneaky types who sign up and then come back a couple days later to post a spam URL.