  We present a new "collisional grooming" algorithm that enables us to model
images of debris disks where the collision time is less than the Poynting
Robertson time for the dominant grain size. Our algorithm uses the output of a
collisionless disk simulation to iteratively solve the mass flux equation for
the density distribution of a collisional disk containing planets in 3
dimensions. The algorithm can be run on a single processor in ~1 hour. Our
preliminary models of disks with resonant ring structures caused by terrestrial
mass planets show that the collision rate for background particles in a ring
structure is enhanced by a factor of a few compared to the rest of the disk,
and that dust grains in or near resonance have even higher collision rates. We
show how collisions can alter the morphology of a resonant ring structure by
reducing the sharpness of a resonant ring's inner edge and by smearing out
azimuthal structure. We implement a simple prescription for particle
fragmentation and show how Poynting-Robertson drag and fragmentation sort
particles by size, producing smaller dust grains at smaller circumstellar
distances. This mechanism could cause a disk to look different at different
wavelengths, and may explain the warm component of dust interior to Fomalhaut's
outer dust ring seen in the resolved 24 micron Spitzer image of this system.
