We firstly review some of the recent developments which firmly establish GaMnAs as a well understood carrier mediated ferromagnetic semiconductor. We then introduce and discuss the tunnelling anisotropic magnetoresistance and Coulomb blockade anisotropic magnetoresistance. These effects have recently been discovered in GaMnAs heterostructures and nanostructures. These effect should be present in other magnetic systems with strong spin-orbit coupling and may well prove to be of importance in a wide range of materials. In normal tunnelling magnetoresistance, spin conserving tunnelling results in low/high resistance states for parallel/anti-parallel magnetisations of two ferromagnetic layers. Very recently it has been demonstrated experimentally and theoretically that a large tunnelling anisotropic magnetoresistance, which arises from the dependence of the tunnelling density of states on the orientation of the magnetisation with respect to the crystallographic axes, is present in ferromagnetic tunnelling structures. This leads to strong magnetoresistance in vertical devices in which tunnelling occurs between a single (Ga,Mn)As layer and a non-magnetic layer. It has also been discovered that the tunnelling anisotropic magnetoresistance effects of ~100,000% can be achieved in tunnelling structures with two FS contacts. We show that TAMR is present in a range of vertical tunnelling structures. Recently, in lateral nanoconstrictions, we demonstrated ~400% MR effects which we ascribed to TAMR. Very recently we have observe low-field hysteretic magnetoresistance in a (Ga,Mn)As single electron transistors which can exceed three orders of magnitude. Experimental data are interpreted in terms of electrochemical shifts associated with magnetization rotations. This Coulomb blockade anisotropic magnetoresistance is distinct from previously observed anisotropic magnetoresistance effects as it occurs when the anisotropy in a band structure derived parameter is comparable to an independent scale, the single electron charging energy.

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