  We propose a class of three-dimensional metamaterial architectures composed
of a single doped semiconductor (e.g., n-Si) in air or vacuum that lead to
unusual effective behavior of the classical Hall effect. Using an anisotropic
structure, we numerically demonstrate a Hall voltage that is parallel---rather
than orthogonal---to the external static magnetic-field vector ("parallel Hall
effect"). The sign of this parallel Hall voltage can be determined by a
structure parameter. Together with the previously demonstrated positive or
negative orthogonal Hall voltage, we demonstrate four different sign
combinations
