I heard about this feature in a commercial web-based family tree service and thought it was a great idea, and one that PGV could implement:
Users can subscribe to Individuals or maybe Family records and be notified of any changes to those records.
Sorry if this isn't the right place to suggest new features these days - looks like there's some talk of moving these forums…
To submit a feature request you should better use the assigned tracker:
But if you ask for my opinion it will be too complex for most users. I check sometimes how often they use the favorites, very seldom.
What they really like is to check my box with the latest changes. All what they have to do is to surf on the startpage at least once a month and check if there is something interesting.
I have about 500 users at the moment.
…then there's always the RSS feed. That can provide the latest changes list too.