On my Android, (and my kiddo’s phone) I use Where’s My Droid. This is a very handy app, responding to SMS messages. I can simply send an SMS to a specific phone, and the response includes the location on Google Maps. Read about it and download from here: http://wheresmydroid.com/
On my Symbian Phone, I’m using Phonelocator Periodic. By using the mobile application Phonelocator Periodic, I can track my phone and watch its location on Google Maps. By adding a “buddy mobile number” into the application, I can use my buddy’s phone to set up an alarm if the phone is stolen. A simple SMS command will trig an annoying alarm on my phone (in the pocket of the thief), making the phone unusable.
I strongly recommend the application, available on OVI store.