Haptic Interfaces for the Permanently or Temporarily Blind

Thinking out loud:

We're all aware of mobile phones that vibrate to tell us about a call or a message.  What about other really useful haptic interfaces?  Those that utilize our sense of touch?

It seems to me like there should be lots of lots of ways to utilize our sense of touch in situations where folks are temporarily or permanently blind.

Simple case: imagine a person driving a car and turning on his left-turn-signal to indicate a lane change. A camera embedded in the car notices another vehicle that's possibly in the drivers "blind spot."  The car reacts by delivering a short vibrating “buzz” to the drivers lower back (on his left side).  A useful, passive indicator for short-term blindness (doesn't even interrupt his conversation with the passenger!).

More extreme case: imagine a blind person approximating sightedness with the use of a simple device. Like the kids toy that is made up of hundreds of tiny silver pins (fun to create a rendering of your hand), a thin device with a large number of “pins” would be placed across the back of a blind person (or whatever part of the human body that is both large and sensitive enough). Paired with a modified GPS device and simple camera, a blind person could walk down the street and have a simplified rendering of his surroundings – there is a street there, another street there, a car is moving along here, a person is walking towards me here (a “scratching” feeling would move from his lower back to his upper back), etc. Given our ability to learn by repetition, I would imagine these haptic cues would slowly become second nature to the blind person and would help inform their behavior and movements.