Ultra-low density (<20 mg/cm3) nanoporous materials are desirable for a number of applications in materials for energy storage, generation, and utilization. Yet such materials are frustratingly difficult to fabricate as well-defined macroscopic structures. The few materials that have historically been fabricated to these specifications (e.g., SiO2, Fe2O3, C) often require complex, multistep syntheses and/or highly specialized equipment. Herein will be discussed recent developments at Lawrence Livermore National Laboratory to produce high-quality metal foams approaching 1 mg/cm3 from nanowire suspensions via a facile freeze-casting approach. Focus will be placed on successes in expanding our compositional repertoire and insights gained as to the evolution of pore structures during non-aqueous and mixed-solvent freeze-casting via ultra-small-angle X-ray scattering and computed tomography. This work was performed under the auspices of the U.S. DOE by LLNL under Contract DE-AC52-07NA27344.