[Saoirise]

I dated someone who had an application on their phone that could find where your cell phone was, thus where you were. They would enter in a cell number to the application and be able to locate you/cell via the GPS. We didn't date long ;)

[Mogger]

Try clicking here: http://aprs.fi/moving/

Scroll down and randomly click on a call sign.

Zoom in on the map and click on a red waypoint for info.

Use your "back" button and pick another.

This Ham radio system is known as APRS. Handy and a lot of fun.

You'll see it's used a lot more in the rest of the world than in the USA.

Notice the speeds. A lot of ships, some aircraft.

[Blueflag]

GPS not even needed. The cell network alone can be pretty discrete, especially in urban areas.