Multiple-image gravitational lens systems are powerful tools for addressing a wide range of astrophysical and cosmological issues, from galaxy mass distributions and evolution to the Hubble constant and vacuum energy density. First, I present results from the recently completed Cosmic Lens All-Sky Survey (CLASS), which searched for gravitational lensing among compact radio sources in the northern sky. CLASS has discovered ~20 lenses, and currently provides the largest uniformly-selected sample of gravitationally lensed quasars. Second, I review what we have learned from the investigation of individual lens systems and the CLASS lens sample as a whole. Finally, I outline the prospects for continued astrophysical and cosmological studies using strong gravitational lensing.