• Grab an old cell phone (make sure it has GPS).
• Turn on its Internet access.
• Tweak the settings. Presumably, you're only going to use this for vehicle tracking. Set the ringer volume to 0 and mute the keypad.
• Next step is choosing a tracking/mapping service. InstaMapper (free) or AccuTracking (about $6/month)
• The final step is the trickiest. For real 24/7 tracking, you'll need to hardwire the phone to your car's battery. (more)