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 known. 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. Observations of these extreme galaxies provide a unique opportunity to test our fundamental understanding of galaxy formation, the particle nature of dark matter, and the standard cold dark matter model of cosmology.

However, even with our most powerful telescopes, searches for the faintest galaxies are still limited to our own "cosmic backyard". I will describe recent advances in the census of our galactic neighborhood, and how observations of our smallest galactic neighbors can help answer some of the biggest questions in cosmology.