We give an efficient algorithm for computing Fourier expansions of weight 2 cusp forms of prime level. The algorithm is based on Mestre's Methode des Graphes and supersingular isogeny graphs, and was used to greatly expand tables in the LMFDB. We'll also talk briefly about work in progress with Kimball Martin about heuristics for estimating the number of degree 2 cusp forms up to a given level.