  We compute the gravitational quasinormal modes of the global
AdS_5-Schwarzschild solution. We show how to use the holographic dual of these
modes to describe a thermal plasma of finite extent expanding in a slightly
anisotropic fashion. We compare these flows with the behavior of quark-gluon
plasmas produced in relativistic heavy ion collisions by estimating the
elliptic flow coefficient and the thermalization time.
