The observation that the cosmic expansion is accelerating suggests that the value of the cosmological constant is meV-scale. From a theoretical perspective, this value is fine-tuned, and the expectation is that it should be much larger. In this talk, I will describe recent progress towards resolving this "cosmological constant problem". In this proposal, the Universe is pervaded by a superfluid that can counteract the effects of an arbitrary cosmological constant. The superfluid can equivalently be viewed as a sector of Lorentz-violating massive gravity. I will explain how to construct stable theories, and their potential observational phenomenology. I will conclude by presenting some recent progress in constructing realistic cosmological models.