  Several groups have recently computed the gravitational radiation recoil
produced by the merger of two spinning black holes. The results suggest that
spin can be the dominant contributor to the kick, with reported recoil speeds
of hundreds to even thousands of kilometers per second. The parameter space of
spin kicks is large, however, and it is ultimately desirable to have a simple
formula that gives the approximate magnitude of the kick given a mass ratio,
spin magnitudes, and spin orientations. As a step toward this goal, we perform
a systematic study of the recoil speeds from mergers of black holes with mass
ratio $q\equiv m_1/m_2=2/3$ and dimensionless spin parameters of $a_1/m_1$ and
$a_2/m_2$ equal to 0 or 0.2, with directions aligned or anti-aligned with the
orbital angular momentum. We also run an equal-mass $a_1/m_1=-a_2/m_2=0.2$
case, and find good agreement with previous results. We find that, for
currently reported kicks from aligned or anti-aligned spins, a simple kick
formula inspired by post-Newtonian analyses can reproduce the numerical results
to better than $\sim$10%.
