I've been having fun with a new "toy." A nice little handheld GPS (global positioning system) receiver bought at a bargain price at a local big box store. Following my progress on the scrolling map image during a morning commute made the trip a lot more fun.
Surprising to me was how quickly the GPS was able to update and display my travel speed as I drove. After all, the little palm-sized unit was receiving signals from several orbiting satellites a little more than 12,000 miles high, comparing their time signals, calculating my position in three dimensions and its rate of change, and displaying it on a little LCD screen, all with only a couple of seconds lag time! And, optimally, to within about 10 feet of my exact location. Following travel progress on the unit's built-in map was fun (for map geeks like me) but a little too distracting if you're driving. I'm looking forward to my next stint as a passenger!