For a few years now, socially-minded tinkerers have been building various systems for locating friends in bars. The most popular approach to solving this problem technically has been to dump the required computation about where you are to the user (see Imahima and Dodgeball, for instance). The problem is that to shout “Here I am!” users have to learn to input the commands, which is a bit clumsy even on i-mode phones. Another approach has been to use GPS or cellular positioning, but even where the technology is available, it’s not precise enough. A third way is the check-in/check-out approach, where some piece of technology (usually a low-cost card-swiper, infrared beacon, or RFID reader) is installed in the physical setting and users carry some sort of ID tags. There the problem is the cost and scalability. When building the Aula space for instance, we wanted for there to be a graceful way to let other members know when you’re there. After months of negotiations with the building management, wiring the door locks, and scavenging hardware, we managed to get the RFID-based Hunaja system working. But transferring the system to other premises was too costly, and so we had to shut Hunaja down when Aula left that space. The fourth and most recent solution is to do the tracking with WiFi or Bluetooth, although users then need an expensive terminal. Even if no one has quite figured it out yet, there might be a niche for a business model here, because (some) proprietors are willing to pay to attract a community of regulars, and (some) people will pay to publish their whereabouts to their small worlds when they’re out in town. (Although for sure it does have its problems, like stalking.)