  We review recent interest in the relativistic Riemann problem as a method for
generating a non-equilibrium steady state. In the version of the problem under
con- sideration, the initial conditions consist of a planar interface between
two halves of a system held at different temperatures in a hydrodynamic regime.
The new double shock solutions are in contrast with older solutions that
involve one shock and one rarefaction wave. We use numerical simulations to
show that the older solutions are preferred. Briefly we discuss the effects of
a conserved charge. Finally, we discuss deforming the relativistic equations
with a nonlinear term and how that deformation affects the temperature and
velocity in the region connecting the asymptotic fluids.
