I bought a phone-sized projector containing WiFi, Bluetooth and an Android OS and was very impressed - pretty cheap as well. It's perfect for occasions when you need to look at a reasonable size image on a very portable device. The LED projection is bright enough to see in shaded daylight up to about A3 size, and in a dark room will project very watchable movies on a wall or screen several metres in size. Battery charge lasts over 2 hours of continuous projector use.
So my idea would be a phone with a normal size display, but with a projector lens on the edge for when you need to see some reasonable detail or display something to a group of people.