  In hierarchical structure formation models of disk galaxies, a dark matter
disk forms as massive satellites are preferentially dragged into the disk-plane
where they dissolve. Here, we quantify the importance of this dark disk for
direct and indirect dark matter detection. The low velocity of the dark disk
with respect to the Earth enhances detection rates in direct detection
experiments at low recoil energy. For WIMP masses M_{WIMP} >~ 50 GeV, the
detection rate increases by up to a factor of 3 in the 5 - 20 keV recoil energy
range. Comparing this with rates at higher energy is sensitive to M_{WIMP},
providing stronger mass constraints particularly for M_{WIMP}>~100 GeV. The
annual modulation signal is significantly boosted by the dark disk and the
modulation phase is shifted by ~3 weeks relative to the dark halo. The
variation of the observed phase with recoil energy determines M_{WIMP}, once
the dark disk properties are fixed by future astronomical surveys. The low
velocity of the particles in the dark disk with respect to the solar system
significantly enhances the capture rate of WIMPs in the Sun, leading to an
increased flux of neutrinos from the Sun which could be detected in current and
future neutrino telescopes. The dark disk contribution to the muon flux from
neutrino back conversion at the Earth is increased by a factor of ~5 compared
to the SHM, for rho_d/rho_h=0.5.
