Recent applications of mormhological stability theory are reviewed. For growth of a binary alloy from the melt, the temperature-dependence of the solute diffusivity can have a significant effect on the critical wavelength at the onset of instability. The response of the interface velocity to an electrical current pulse has been calculated by a linear perturbation analysis. The effect of a parallel shear flow and anisotropic interface kinetics on the onset of instability during growth from a supersaturated solution has been analyzed. The kinetic anisotropy arises from a model of step motion in which the morphological instability corresponds to step bunching. Kinetic anisotropy causes traveling waves along the crystal-solution interface and an enhancement of morphological stability. A shear flow in the direction of the step motion promotes morphological instability, while flow in the opposite direction is stabilizing. Oscillatory (in time) shear flows can be studied by Floquet theory.