Searching for new physics in the primordial density perturbation

Over the last decade, considerable effort has been expended to understand how subtle correlations in the pattern of hot- and cold-spots in the cosmic microwave background anisotropy, or the details of galaxy clustering, can teach us about physics at very high energies. I will review this effort and explain how it enables us to use large-scale structure in the universe as a particle detector, before looking forward to the prospects for near- and medium-term observations.