The Fomin-Kirillov algebra epsilon(n) is a noncommutative quadratic algebra with a generator for every edge of the complete graph on n vertices. For any graph G on n vertices, we define epsilon(G) to be the subalgebra of epsilon(n) generated by the edges of G. We show that these algebras have many parallels with Coxeter groups and their nil-Coxeter algebras: for instance, epsilon(G) is a free epsilon(H)-module for any H subset of G, and if epsilon(G) is finite-dimensional, then its Hilbert series has symmetric coefficients. We determine explicit monomial bases and Hilbert series for epsilon(G) when G is a simply laced finite Dynkin diagram or a cycle, in particular showing that epsilon(G) is finite-dimensional in these cases. We also present conjectures for the Hilbert series of epsilon((D) over barn), epsilon((E) over bar6), and epsilon((E) over bar7), as well as the graphs G on six vertices for which epsilon(G) is finite-dimensional.