  Over the last few years enormous progress has been made in the numerical
description of the inspiral and merger of binary black holes. A particular
effort has gone into the modelling of the physical properties of the final
black hole, namely its spin and recoil velocity, as these quantities have
direct impact in astrophysics, cosmology and, of course, general relativity. As
numerical-relativity calculations still remain computationally very expensive
and cannot be used to investigate the complete space of possible parameters,
semi-analytic approaches have been developed and shown to reproduce with very
high precision the numerical results. I here collect and review these efforts,
pointing out the relative strengths and weaknesses, and discuss which
directions are more promising to further improve them.
