  We prove a shape theorem for rotor-router aggregation on the comb, for a
specific initial rotor configuration and clockwise rotor sequence for all
vertices. Furthermore, as an application of rotor-router walks, we describe the
harmonic measure of the rotor-router aggregate and related shapes, which is
useful in the study of other growth models on the comb. We also identify the
shape for which the harmonic measure is uniform. This gives the first known
example where the rotor-router cluster has non-uniform harmonic measure, and
grows with different speeds in different directions.
