[fragmede]

If I'm holding the phone in landscape with thumbs on front and fingers on the back, what I'd really like is buttons on the back so I'm not limited to just my thumbs. Shift, spacebar and an 'alternate layout' button (switches the onscreen keyboard to symbols/accents) come to mind. Maybe navigation buttons so you don't need to constantly shift your hand to reach the hardware buttons.

That said, many flip phones do actually have dual screens. Never seen them used simultaneously though. (Woz's solution for multitasking also comes to mind - just have two phones.)