The alkali-halide cyanide systems, e.g., (KBr)1-x(KCN)x show a cubic room temperature phase with dynamic orientational disorder of the aspherical CN ions. At low temperatures the CN-rich compounds order ferroelastically whereas for lower CN concentrations an orientational glass is formed. The experimental results and the present state of understanding will be reviewed with emphasis on the anomalous structural and elastic behaviour at the crossover from one type of transition to the other.