One issue with GPS is that it can be difficult to look at the GPS device safely while driving in heavy traffic. However, people who are deaf cannot rely on audio information. So, I propose a GPS which hooks to a person's body (I leave it to the designers to pick an ideal place). The GPS would not use braille (deaf people don't' usually know it and blind people shouldn't be using the device). Instead, it would use a simplistic form of pressure. A left turn would provide pressure to the left, with the pressure moving towards some sort of point on the gps which represents the vehicle itself.

The technology to produce such a device already exists, but the market is admittedly rather limited.