Geospatial Vibrating Belt
This geospatial vibrating belt called FeelSpace seems pretty interesting, and has a lot of potential to help aid the blind potentially. It currently is designed to "point" to north all the time, but with a bit of sonar, I'm sure it would be a lot better.
This belt is equipped with a set of vibrators controlled by an electronic compass: the element pointing north is always slightly vibrating. That way, the person wearing the belt gets permanent input about his heading relative to the earth's magnetic field.