  We review a recently developed formalism for computing thermoelectric
coefficients in correlated matter. The usual difficulties of such a calculation
are circumvented by a careful generalization the transport formalism to finite
frequencies, from which one can extract the high frequency objects. The
technical parallel between the Hall constant and the Seebeck coefficient is
explored and used to advantage. For small clusters, exact diagonalization gives
the full spectrum for the Hubbard and especially the $t$-$J$ model, a
prototypical model for strong correlations, and this spectrum can be used to
compute the exact finite frequency transport coefficients and hence to
benchmark various approximations.
  An application of this formalism to the physically important case of sodium
cobaltate $Na_xCoO_2$ is made, and interesting predictions for new materials
are highlighted.
