For more than a decade, the 570-megapixel Dark Energy Camera (DECam), mounted on the 4-meter Blanco Telescope in Chile, has been the premier optical/near-infrared survey instrument in the southern hemisphere. I will highlight several recent advances in near-field and far-field cosmology that were made possible by the exceptional speed, depth, and quality of the DECam observations. These and many other results from DECam were enabled by the computational resources and expertise at the National Center for Supercomputing Applications at the University of Illinois.