― John Barman
Sure, you could just buy a shocking painting or something and hang it in the middle of the living room wall, but even then, the impact is focused on a single spot. No, for true wow-factor, you need discordant décor.
Another way to play with light is to play with the actual light in the room, although this technique alters the feel of the room (and possibly its utility) more than you might want it to. For instance, a home office is usually bright, so make it dim instead―eliminate any room light (ceiling fixtures, etc.) and use small, strategically-placed reading lamps instead. Or go the other way in the living room―instead of a dim room for watching TV, make it bright by uncovering windows, and installing multiple light sources. The great thing about playing with light in this way is that it's easily reversible if you change your mind.