When managing events with large amounts of invitees, it can be pretty tedious opening every single registrant / participant record in order to confirm nicknames, custom addressee fields, spouse, whether or not the spouse is a constituent, etc...  By adding in functionality similar to the batch entry constituent window to the Events Participant tab, I'd be able to retrieve this info at a glance.  It can take a very long time to go to each record to update RSVP responses and this would streamline confirming basic information, including differentiating registrants that have the same first and last name.