The Spatial Standard Observer (SSO) was developed in response to a need for a simple, practical tool for measurement of visibility and discriminability of spatial patterns. The SSO is a highly simplified model of human spatial vision, based on data collected in a large cooperative multi-lab project known as ModelFest. It incorporates only a few essential components, such as a local contrast transformation, contrast sensitivity function, local masking, and local pooling. The SSO may be useful in a wide variety of applications, such as evaluating vision from unmanned aerial vehicles, measuring visibility of damage to aircraft and to the shuttle orbiter, predicting outcomes of corrective laser eye surgery, inspection of displays during the manufacturing process, estimation of the quality of compressed digital video, evaluation of legibility of text, and predicting discriminability of icons or symbols in a graphical user interface. In this talk I will describe the development of the SSO, and will discuss in detail a number of these potential applications.