The dynamical distribution of galaxies within clusters has long been used to infer the mass of clusters. However while the mass is an inferred quantity, the gravitational potential is an observed quantity. For instance, the galaxy radius/velocity phase-space has a well-defined escape-velocity surface which is the Newtonian potential profile. A similar observable when using the temperature and density of the intra-cluster medium. I will discuss new techniques for measuring the gravitational potential and how it can be used for precision cosmology. The potential is also a physically meaningful measure of environment and can be applied to studies of galaxy evolution and as a direct probe of the theory of gravity on large scales.