[polymythic] Is helping the blind see with his haptic feedback device called HALO. At the heart of the device is an Arduino Mega 2560 which senses objects with a few ultrasonic range finders and then relays the information back to the user using some vibration motors from old cell phones. The user can feel the distance by the frequency at which the motor pulses. The faster the motors pulse the closer an object is.
This kind of sensing is something that it can be applied to pretty much any sensor allowing the user to feel something that might be otherwise invisible. While haptic feedback is nothing new its good to see continuing work with new sensors and different setups.