Suggestions/thoughts...

It would be great if there was a way to do a mass action on a whole list of invited people - to send multiple reminders or to delete their invitations.

Is there a way to track whether or not an invitation has been read/deleted?

Also, it would be cool if there were an admin interface that kept a history of who has been invited, (regardless if they had been deleted by the inviter), and kept stats on who did or didn't join.