MapBag
Josh wanted to wander the streets of Chicago on his bike while ensuring he was heading in the general direction of his destination. He therefore created the MapBag, a LilyPad Arduino-based “proprioceptive augmentation device.” Here’s how it works:

The MapBag contains a small microcontroller, a GPS chipset, and a series of 8 vibration motors sewn into the bag. The microcontroller constantly evaluates the wearer’s current heading and the location of magnetic North, or the relative location of a user-defined waypoint (such as home). The microcontroller informs the wearer of compass information through the vibration motors, basically allowing you to read a compass with your body.

After using the MapBag for a few weeks, the slight pulses used to convey heading information have become second nature. Most importantly, I no longer find myself using street signs or depending on landmarks to discern my position in the city’s grid.

[via Hack A Day]