The overall goal of Zen interior design is to create a peaceful, inspiring home that looks good without looking dressed up. Combine any or all of the following elements of Zen decorating:
♦ Clean straight lines: nothing that’s visually busy;
♦ Built-in, concealed storage;
♦ Open, clear spaces (zero clutter);
♦ Natural, beautiful but unfussy materials;
♦ Quality but simple furnishings: nothing ‘bling’ or high-maintenance, nothing that screams for attention or tries to impress;
♦ Low-impact colors taken from nature, a minimum of (subtle) pattern;
♦ Quality rather than quantity;
♦ A calm overall look (you get enough stimulation when you step outside the front door 😉 )

as well as a little blurb all about Japanese Zen
http://plato.stanford.edu/entries/japanese-zen/
Generally speaking, Zen cherishes simplicity and straightforwardness in grasping reality and acting on it “here and now,” for it believes that a thing-event that is immediately presencing before one’s eyes or under one’s foot is no other than an expression of suchness, i.e., it is such that it is showing its primordial mode of being. It also understands a specificity of thing-event to be a recapitulation of the whole; parts and the whole are to be lived in an inseparable relationship through an exercise of nondiscriminatory wisdom, without prioritizing the visible over the invisible, the explicit over the implicit, and vice versa.