It is widely known that most applications exhibit locality of reference. That is, applications access only a subset of their pages during any phase of their execution. This subset of pages is usually called the working set of the application. In this note we present the working set of applications in pictorial form so that it can be easily viewed and understood. Based on these working set ``pictures' we make observations about the size, the duration, and the regularity of the working sets of various applications. Our applications cover several domains, ranging from numerical applications, program development tools, CAD simulations, and database applications. Our results suggest that most numerical and some database applications have regular access patterns and good locality of reference. Although most database and program development applications seem to have little locality of reference, careful observations at the appropriate granularity reveal regular and sometimes periodic access patterns.