I’ve tried out a little mobile phone application called “Phone 2 Google Earth” The program communicates with a bluetooth GPS and records your position at regular intervals for as long as required. You can also record placemarks. The data is saved as a KML file, which can be transferred from the phone to a PC. Here is an example google earth file .
The llamas featured as a placemark can be seen on my moblog.
The colour and opacity of the track can be modified once it has been imported to Google Earth via the advanced tab. It would be nice if there was an option to output the data as a GPX file which would preserve other aspects of the GPS log, such as speed and altitude, giving you the choice as to whether to use Google Earth or GPS Visualizer to view the data. As a basic tracking program however, Phone2GEarth works very well, and I’ll use it for fieldwork.