Orangetrack is a GPS fleet tracking service that I have run with a business partner since 2006.
We sell the system to businesses who want to track where all their vehicles are, where they have been, how fast they are going etc.
We install little black boxes in each of the vehicles and program them to send data in realtime back to our servers.
The website contains live updating maps and dashboards so you can see what is happening right now, and a full reporting suite for all the historic data.
Here's a little animation I made showing the movement of the vehicles on Orangetrack over the course of a day.