  We consider the consequences of a matter power spectrum which rises on small
scales until eventually being cutoff by microphysical processes associated with
the particle nature of dark matter. Evolving the perturbations of a weakly
interacting massive particle from before decoupling until deep in the nonlinear
regime, we show that nonlinear structure can form abundantly at very high
redshifts. In such a scenario, dark matter annihilation is substantially
increased after matter-radiation equality. Furthermore, since the power
spectrum can be increased over a broad range of scales, the first star forming
halos may form earlier than usual as well. The next challenge is determining
how early Universe observations may constrain such enhanced dark matter
perturbations.
