I am really fond of things like this. Over at Himalayan Art Resources, they have notice of what they call "diagrammatic prayers," which I suppose conveys the idea. The example, above, is from the entrance to the Dzongsar Institute (now the Deer Park Institute). The trick is that they can be read in any direction, and still remain sensible. Would that we could do the same, eh? Hereabouts (and that would be Taiwan), you can buy little cards like this, and people use them to ward off secret arrows, posting them like mirrors. Visit Zambala at No. 104, Sec. 2, Min-Sheng East Road, Taipei 104, or call 866-2-2100-1919 to see if they're in stock.