Not just the anniversary date, but also the account opening date. Anniversary date changes when you do a product change, but the account opening date never changes. Knowing this date allows you to assess weather closing the account would close an account with a very long credit history.

Along the same lines as this, I would like to see a calendar view of the upcoming annual fees to get ready for retention calls. And alerts/push notifications for when annual fees are posted (or one week prior).