Large amounts of energy can be released when matter falls deep into the gravitational potential of a black hole, and over the past several decades more and more ways this can happen have been discovered. Although these pathways to relativistic accretion are diverse in terms of their astronomical contexts (for example, the masses of the black holes range from a few solar masses to a few billion), the physics involved is much the same for all of them.   This talk will both review the underlying theory and report on new work demonstrating how a direct connection can be made from relativistic orbital mechanics and MHD turbulence to the photon spectra we observe.