Record the gsm tower your cell phone see, use the google api to translate that in cohordinates and geolocate your track. Can work as a very imprecise gps tracker: 400m (well served city) to 2km (countryside) error on your position

You’ll need Nokia to sign the sys file for you, see README before uploading the file to your cell phone.

http://code.google.com/p/nwtracker/