Haptics has come to mean the lackluster vibration your phone gives off when you use the on-screen keyboard, but there's plenty more potential for the technology. Steve Struebing has come up with HALO - Haptic Assisted Location of Obstacles - a headband intended to allow blind or visually-impaired users the ability to navigate without bumping into things.
Video demo after the cut
HALO uses an array of ultrasonic sensors to figure out potential obstacles in the surrounding space, but rather than translate them into radar-style "pings" or "clicks", it uses vibration motors embedded into the headband. The closer you are to an obstacle, the more frequent and/or powerful the vibrations are.
At the heart of it is an Arduino Mega 2560 controller, and it runs off a single 9V battery. Struebing has put together an Instructable showing how the whole thing goes together, and the whole thing can be reasonable inexpensive - certainly in comparison to training up a guide dog.