I've mentioned the concept of design as metaphor before - when one object, in the right setting as another, takes on the qualities of the second object. Useful for turning sideboards in to metaphorical grand pianos and such.
Recently, I returned home to find the monitors on my desk glowing with the underwater hues of the aurora screen saver. Clearly it's not an aquarium, but in a setting where a Bond-villain shark tank wouldn't look out of place, the displays create a cool, and somewhat foreboding ambiance.