Entourage, Entourage, where for art thou Entourage?
Would be an excellent application to get Entourage working on the iPhone. For the Windows afflicted, Entourage is a nice 'productivity' application that's much better than Outlook...
Would be great to sync everything from the Mac and back including tasks and projects. It currently only syncs contacts and (partially) calendars.
This would probably be far more useful on a daily basis than being able to write to Office documents.