With the Tevatron now shut down and slated for decommissioning, it is only natural to think about other possible uses for the 6.3-km tunnel. Given that the brightness of electron storage rings naively scales as radius cubed, one exciting possibility is to build a so-called ultimate storage ring light source. This talk describes a somewhat speculative exploration of this idea, showing the potential for a storage ring x-ray source of unprecedented brightness. In the process, we review the basic physics of storage ring light sources and describe computational approaches to their optimization.