In the latest Accidental Tech Podcast Marco Arment talks about a better way to do Notification Center. One that shows a full list of notifications, instead of only the new ones. It's an interesting discussion but their conclusion is that it may be to complex to do.
Inspired by their discussion I drew a quick sketch of a possible revisioning of the Notification Center. It basically removes the Missed tab, and creates two new views: New and All.
New shows all notifications that weren't opened yet, or whose apps you did not yet launch since the notification was pushed.
All shows you all notifications your device received, regardless of read status.
The Two buttons at the bottom allow for a quick Mark All As Read, and a Delete All.
Optionally, you could reorganise them by App/Source instead of by Date via a toggle the Settings App.