  Collective flow has been observed in heavy ion collisions, with a large
anisotropic component, and ideal hydrodynamic calculations had significant
successful in describing the distribution of produced particles at the RHIC
experiments. In order to account for this near ideal fluid behavior, the shear
and bulk viscosity of the quark gluon plasma (QGP) must be computed from first
principles in a regime where the QGP is not weakly coupled. In this talk I
describe recent progress in computing energy-momentum tensor correlators on the
lattice from which the viscosities can be extracted via Kubo formulas. I also
show how to cumulate information from several channels, including at
non-vanishing spatial momentum, in order to best constrain the viscosities.
These methods should soon yield predictions at the higher temperatures that
will be explored at the LHC experiments.
