Our Milky Way galaxy is surrounded by a flock of tiny satellite galaxies. These ultra-faint "dwarf" galaxies are the most ancient, most chemically pristine, and most dark-matter-dominated stellar systems ever observed. Observations of these extreme galaxies provide a unique opportunity to test the standard cold dark matter model of cosmology, while also providing insights into the formation of galaxies, stars, and the heavy elements. Due to their low luminosity, the discovery of the faintest galaxies has only recently become possible thanks to the unprecedented sensitivity of digital sky surveys. However, even with our most powerful telescopes, our searches are limited to our own "cosmic backyard". I will describe recent advances in our census of the Milky Way's neighborhood, and how observations of our smallest galactic neighbors are helping answer some of our biggest questions.
