  Fast X-ray timing can be used to probe strong gravity fields around collapsed
objects and constrain the equation of state of dense matter in neutron stars.
These studies require extremely good photon statistics. In view of the huge
collecting area of its mirrors, XEUS could make a unique contribution to this
field. For this reason, we propose to include a fast X-ray timing capability in
the focal plane of the XEUS mirrors. We briefly outline the scientific
motivation for such a capability. We compute some sensitivity estimates, which
indicate that XEUS could provide better than an order of magnitude sensitivity
improvement over the Rossi X-ray Timing Explorer. Finally, we present a
possible detector implementation, which could be an array of small size silicon
drift detectors operated out of focus.
