A lot of that stuff shows up on the home page, if you're looking at it; you get notified for upvotes or "thank you"s for answers, and the questions that show up there are the ones that it marks as being of interest (though that seems to be based solely on the topics you're watching).

The email notifications are a lot more sparse, presumably by design (to avoid drowning people in the stuff). A weekly summary (upvotes, thanks, and particularly active topics of interest) might be nice...