Multilayer x-ray optics are currently finding use in several types of applications. Although the performance of silicon-based and carbon-based multilayer mirrors is adequate for some of these applications, new material pairs that would improve performance at several crucial wavelengths are necessary to make many new technologies feasible. We describe a procedure for selecting these new materials that considers both the optical and structural requirements of thin films for high-reflectivity mirrors. We identify material pairs that merit future study for use in both amorphous and superlattice multilayer mirrors. Preliminary results on the growth of two of these new material pairs, Ag/B and PdxB1-x/B, are summarized. In work performed to date on Ag/B, the polycrystalline layers that formed were not structurally perfect enough to form good multilayer mirrors. However, further study of this material pair is warranted. The PdxB1-x/B multilayers were produced by alternately depositing palladium and boron. X-ray and electron diffraction indicate that these multilayers are amorphous and are of high structural quality. Auger electron spectroscopy and x-ray photoelectron spectroscopy experiments on single interface samples indicate that these materials react to form PdxB1-x/B with x ≈ 0.9.