If you go to the apple website and watch the OSI 5 update video, it pretty much shows most of the new features that will be included in the iPhone 5. It's actually pretty neat. As far as any features I think it should have? I can't tell you because Apple hasn't told me what to think yet.
I think the iPhone 5 should have the iCloud feature to operate iTunes for wireless remote access of music from all mobile devices and computers. It is also rumored that it will run on iOS 5, which will have more than 200 new features that will include new stand, improved notifications system and iMessage.