This paper briefly reviews a few selected technologically important areas where Molecular Beam Epitaxy has been used to advantage. These include the use of MBE to study and improve ohmic and Schottky metallizations to GaAs and the invention of new types of variable barrier height diodes. The proven potential of MBE grown ternary alloy structures as materials for enhanced microwave and high speed digital devices and the use of selected area epitaxy for state of the art digital integrated circuit elements are also discussed.