I was thinking about digital photo frames and how they are pretty decent at just leaving a static image in place. Wouldn't it be an interesting idea to have a phone with a wrap around removable back completely made of color e-ink that would take pictures designed for that specific resolution/size? A wallpaper could turn the camera hump into the sun, have the edges look like textured leather and whatever your imagination allows. The case would simply have a connection it makes when you snap it in. This way it could be replaced with something else and let you remove battery and other stuff. It could have other uses like preview selfies while shooting pictures with the rear camera. It could include more complex touch interactions but then the cost would likely go too high. In those cases if you had screen down you could double tap to quickly see notifications, enable swipe gestures and many other things. Not sure this is something consumers would bite though. It would have to launch with some pretty designs.