  We show that the presence of a rho~1/r^{3/2} dark matter overdensity can be
robustly predicted at the center of any galaxy old enough to have grown a
power-law density cusp in the stars via the Bahcall-Wolf mechanism. Using both
Fokker-Planck and direct N-body integrations, we demonstrate collisional
generation of these dark matter "crests" (Collisionally REgenerated
STtructures) even in the extreme case that the density of both stars and dark
matter were previously lowered by slingshot ejection from a binary supermassive
black hole. The time scale for collisional growth of the crest is approximately
the two-body relaxation time as defined by the stars, which is < 10 Gyr at the
centers of stellar spheroids with luminosities comparable to that of the Milky
Way bulge or less. The presence of crests can robustly be predicted in such
galaxies, unlike the steeper enhancements, called "spikes," produced by the
adiabatic growth of black holes. We discuss special cases where the prospects
for detecting dark matter annihilations from the centers of galaxy haloes are
significantly affected by the formation of crests.
