The South Pole Telescope has systematically identified large numbers of high-redshift strongly gravitationally lensed systems. These sources are selected by their extreme mm flux, which is largely independent of redshift and lensing configuration. We are undertaking a comprehensive and systematic followup campaign to use these "cosmic magnifying glasses" to study the cosmic infrared background in unprecedented detail, conduct detailed investigations of the properties of massive galaxies at z~1, inform the condition of the interstellar medium in massive galaxies close to the end of the epoch of reionization, and place limits on dark matter substructure. I will discuss the scientific context and potential for these strongly lensed SMGs, give an overview of our team's extensive followup efforts, and describe our preliminary science results, including recent observations with HST and ALMA.