The collision of two black holes is thought to be one of the most energetic events in the universe, emitting in gravitational waves as much as 5-10% of the rest mass energy of the system. An international effort is currently underway to detect gravitational waves from black hole collisions and other cataclysmic events in the universe. The early success of the detectors will rely on the matched filtering technique to extract what are, by the time the waves reach earth, very weak distortions in the local geometry of space and time. In the case of black hole mergers numerical simulations are needed to obtain predictions of waveforms during the final stages of coalescence. 2005 was a watershed year for numerical simulations of black holes, and we are now beginning to explore the fascinating landscape of black hole collisions in the fully non-linear regime of Einstein's theory. In this talk I will give an overview of the recent successes and what we have learned about the merger process, for astrophysically relevant binaries and, time permitting, more esoteric configurations. The latter include hyperbolic encounters fine-tuned to an approximate threshold of merger, exhibiting behavior similar to "zoom-whirl" geodesics in a black hole background. These types of orbits may have some relevance to speculative black hole formation by parton collisions at the LHC in large extra dimension scenarios.

Frans Pretorius