  We present an overview of recent efforts to calculate the interactions among
hadrons using lattice QCD. After outlining the techniques that are used to
extract scattering parameters, we detail the latest calculations of meson-meson
scattering, baryon-baryon scattering and multi-meson systems obtained with
domain-wall valence quarks on the staggered MILC lattices by the NPLQCD
collaboration. Estimates of the computational resources required to achieve
precision results in the baryon sector are presented.
