Stepping through the landscape on waypoint at a time

While out walking this morning I got to thinking about how hard it would or wouldn't be to build an electronic compass.
You know the type of thing, a hand held unit, with an electronic display that mimics the actions of a real compass.  Being electronic it could be paired with a GPS unit via some form of Personal Area Network (PAN).
 How hard can it be.  A lot of the functionality has probable already been engineered into an integrated circuits.

Watch this space.