Formation of metal nitrides to activate dinitrogen is one avenue to ammonia and other nitrogen compounds. Attractive aspects are operation at atmospheric pressure and moderate temperatures, formation of stable chemical intermediates rather than reliance on somewhat sensitive heterogeneous catalysis, and inexpensive materials. If a single metal is used, however, one encounters tradeoffs somewhat akin to the well-known tradeoffs for Haber-Bosch catalysts. Results will be presented for metal nitride-based ammonia synthesis, and new metal alloys that can address some of the tradeoffs between affinity for nitrogen, and formation of ammonia when hydrogen is added. Options using water instead of hydrogen will also be included.