numerical simulations of black hole binaries have made tremendous progress over the last years. the usefulness of such simulations is limited by their tremendous computational cost, which ultimately results from a separation of time-scales: emission of gravitational radiation drives the evolution of the binary toward smaller separation and eventual merger. the time-scale for inspiral is far longer than the dynamical time-scale of each black hole. therefore, the currently deployed explicit time-steppers are severely limited by courant instabilities. implicit time-stepping algorithms provide an obvious route around the courant limit, thus offering a tremendous potential to speed up the simulations. however, the complexity of einstein's equations make this a highly non-trivial endevour. this talk will first present a general overview of the status of black hole simulations, followed by a status report on the ongoing work aimed at implementing modern implict/explicit (imex) evolution schemes for einstein's equations.