Galaxies like the Milky Way are surrounded by large halos of hot gas (a few million degrees) that may contain about half of the baryons “missing” from the disk. Cooling from these halos could provide most of the fuel for star formation over the history of the Universe, but many uncertainties remain, including how this gas interacts with outflows from the galaxy disk. I will describe two recent projects: detecting and characterizing dust outside of nearby, edge-on spiral galaxies using GALEX and Swift ultraviolet photometry, and measuring the rotation of the hot gas around our Galaxy with the XMM-Newton Reflection Grating Spectrometer. By measuring the basic properties of the halo gas, we can begin to understand its role in galaxy evolution.