Superconductor/insulator (SI) superlattices may be viewed as repeated (or stacked) SIS junctions connected in series. Such superlattices have a number of promising applications which we will survey. In the weakly coupled (tunnel junction) limit the possibility of fabricating high resolution X-ray detectors is being studied. For more strongly coupled junctions involving Josephson coupling, possible applications are numerous. The suggestion of Auvil and Ketterson that an SI multilayer would function as an efficient radiation source (due to coherent radiation from the layers and an increased junction phase velocity) has yet to be studied experimentally. Rippert and Ketterson have proposed that a phonon maser might be realized involving 2Δ recombination phonons and internal feedback via the superlattice Bragg mirror. Lomatch et al. have suggested that the added kinetic inductance of a multilayer could be used to eliminate stripline inductors from a Josephson transmission line. Finally multilayer SI tapes have been shown to have an enhanced critical current density, Jc. The mechanisms involved in the above devices and the status of efforts to fabricate them are reviewed.