I was thinking this too... i was thinking "flashlight button".

Problem here is that button needs somesort gpio expander to get it on the bus.
i think the proximity sensors can be used to detect some easy gestures wave hand over, and it shows something else for 2 sec.

(I noticed that after i changed the oled to white one, it looks now like my N9 and i'm tapping on the backside to wake it up...)