A tip for UX'ers and product designers: next time you're out in public, put your glass slab away and observe how others are using theirs.
Don't be intrusive, don't invade anyone's privacy; get close enough to observe interactions, but not close enough to read the screen. Take notes.
Landscape or portrait? Flick-scroll or thumb-pull? Content consumption or production? Two hands or one? Leaning in or lounging back? Device and OS?
Why? We tend to think of the finished product as a sleek screen, divorced from reality. The truth, however, is that the things we produce are actually going to be experienced in a very three-dimensional world.
Observing the ways people interact with their devices in situ is illuminating, and may inform the way you design your next product. For example, I recently saw a woman in a coffee shop perusing TED.com on her laptop; I couldn't resist the urge to see how she navigated our site, where she paused, and when she finally left. Talk about field testing!
So go out and watch users in the wild. It's free ethnographic research, and it's all around you.