Searches for axion dark matter particles have achieved great sensitivity gains in recent years, due largely to the availability of new superconducting amplifiers operating close to the quantum limit. The ADMX-G2 experiment exploits the potential for resonant conversion of axions into photons to place very stringent limits on the existence of dark matter in narrow mass ranges. We will discuss future extensions of ADMX and a new detector concept that could rapidly scan broad regions of the electromagnetic spectrum.