I Make Projects posted plans for "giving yourself a sixth sense for wireless networks" through a small wearable device. It's made from a cannibalized Wi-Fi detector, microcontroller, vibrating motor, and a bit of custom electronics. From the project description:
This project is for a small electronic unit that allows the user to sense the presence and relative signal strength of wireless hotspots. It can be worn as a pendant or carried in a pocket. It is "always on" and communicates the presence and signal strength of an in-range hotspot by way of sequences of pulses – like a heartbeat you can feel. The stronger and faster the "heartbeat", the stronger the wireless signal detected.
Link (via MAKE: Blog)
