1. A method of forming a spacer memory cell, comprising: forming a first electrode, an insulating layer over the first electrode, a second electrode over the insulating layer, and a spacer comprising programmable resistive material in electrical communication with the first and second electrodes, wherein the programmable resistive material has at least two solid phases, and wherein forming the spacer comprises etching a pattern in the insulating layer to define a sidewall on the insulating layer; after said etching, depositing a layer of the programmable resistive material; and anisotropically etching the layer of programmable resistive material to form the spacer along the sidewall on the insulating layer.