  Isospin-violating dark matter (IVDM) generalizes the standard
spin-independent scattering parameter space by introducing one additional
parameter, the neutron-to-proton coupling ratio f_n/f_p. In IVDM the
implications of direct detection experiments can be altered significantly. We
review the motivations for considering IVDM and present benchmark models that
illustrate some of the qualitatively different possibilities. IVDM strongly
motivates the use of a variety of target nuclei in direct detection
experiments.
