Store the geocachers position every minute or so and show as a trail on the map, with small dots. Probably only store the last hour. This should be something that can be turned on/off directly from the Map.
Most Garmin users I know uses the track feature in those GPS devices, and I know I did myself back in the days. I used it when using Neongeo as well.
This idea is 100% inspired by Garmin and Neongeo (obsolete app).
Customer support service by UserEcho