In this talk, I'll begin by giving a broad overview of the recent work by the students and postdocs in our group on star and galaxy formation. The most fundamental unsolved problems in these fields all revolve around "feedback" from stars and black holes, which new generations of theoretical models and simulations are now able to incorporate with increasing predictive power. I'll briefly mention some highlights showing the progress on a number of outstanding mysteries about the nature of dark matter on small scales, and the origins of "universal" properties of stars and galaxies. In the second half of the talk, I'll describe a couple projects in detail exploring a newly-discovered class of instabilities which exist in any system containing dust and gas. These instabilities come in an infinite variety of "flavors" and can have remarkably diverse outcomes. I'll discuss how this may fundamentally change our understanding of dust growth and evolution in the ISM, wind-launching in cool stars and AGN, HII regions, and (of course) planet formation.