This is Arduino code to build a geocache toy using an GPS module, an electronic compass and some neopixel RGB LEDs. It also shows how to calculate the distance and bearing between two points over the Earth. The distance is calculated using the Haversine formula.
See http://marcusjenkins.com/hardware/arduino-based-geocache-finder-toy/
There is no warranty or liability, express or implied in the software. Use it at your own risk. You probably guessed that already.