  In the context of applications of the AdS/CFT correspondence to condensed
matter physics, we compute conductivities for field theory duals of dyonic
planar black holes in 3+1-dimensional Einstein-Maxwell-dilaton theories at zero
temperature. We combine the near-horizon data obtained via Sen's entropy
function formalism with known expressions for conductivities. In this way we
express the conductivities in terms of the extremal black hole charges. We
apply our approach to three different examples for dilaton theories for which
the background geometry is not known explicitly. For a constant scalar
potential, the thermoelectric conductivity explicitly scales as
$\alpha_{xy}\sim N^{3/2}$, as expected. For the same model, our approach yields
a finite result for the heat conductivity $\kappa/T \propto N^{3/2}$ even for
$T \rightarrow 0$.
