  AdS black holes with planar event horizon topology play a central role in
AdS/CFT holography, and particularly in its applications. Generalisations of
the known planar black holes can be found by considering the
Plebanski--Demianski metrics, a very general family of exactly specified
solutions of the Einstein equations. These generalised planar black holes may
be useful in applications. We give a concrete example of this in the context of
the holographic description of the Quark-Gluon Plasma (QGP). We argue that our
generalised planar black holes allow us to construct a model of the internal
shearing motion generated when the QGP is produced in peripheral heavy-ion
collisions. When embedded in string theory, the bulk physics is in fact
unstable. We find however that this instability may develop too slowly to
affect the evolution of the plasma, except possibly for high values of the
quark chemical potential, such as will be studied in experimental scans of the
quark matter phase diagram.
