3 Ludford, P. Frankowski, D. Reily, K. Wilms, K. Terveen, L. 2006 ACM SIGCHI Conference on Human Factors in Computing Systems Montréal, Québec, Canada ACM 889-898 22/04/2006 1-59593-372-7 <p>Although they have potential, to date location-based information systems have not radically improved the way we interact with our surroundings. To study related issues, we developed a location-based reminder system, PlaceMail, and demonstrate its utility in supporting everyday tasks through a month-long field study. We identify current tools and practices people use to manage distributed tasks and note problems with current methods, including the common "to-do list". Our field study shows that PlaceMail supports useful location-based reminders and functional place-based lists. The study also sheds rich and surprising light on a new issue: when and where to deliver location-based information. The traditional 'geofence' radius around a place proves insufficient. Instead, effective delivery depends on people's movement patterns through an area and the geographic layout of the space. Our results both provide a compelling demonstration of the utility of location-based information and raise significant new challenges for location-based information distribution.</p> http://www.grouplens.org/papers/pdf/ludford-chi2006.pdf