The Porter Value Chain as an example of a table in the shape of an arrow, by Gonzalo Medina.
Source: http://tex.stackexchange.com/questions/112579/table-in-the-shape-of-an-arrow/112681#112681
A drawing in TikZ.
The first picture draws an impossible brick, which induces
an optical illusion similar to that triggered by Escher's
impossible cube.
The second picture draws a Penrose triangle, another similar
optical illusion.